JPS6286837A - Wafer conveyor - Google Patents

Abstract

PURPOSE:To convey a wafer without generating particles by disposing a susceptor in a processing chamber, providing a wafer holding electrostatic chuck, and disposing an arm moving from a preliminary chamber to the top of the susceptor in the preliminary chamber. CONSTITUTION:A wafer 8 conveyed from a preliminary chamber 4a to a front chamber 3a is attracted to an electrostatic chuck 5a, and conveyed to a susceptor 205 installed in a reaction chamber 2 by the extension of a conveying arm 5a. Thereafter, after the arm 5a is contracted to move a chuck 6a into the chamber 3a, the chamber 2 is sealed, row gas is diffused from a gas inlet 202 to the surface of the wafer 8 to grow a thin film. After the growth is completed, a chamber 201 is evacuated in high vacuum, a valve 225 is opened, a conveying arm 5b is extended from a front chamber 3b to the chamber 2 to attract the wafer 8 by a chuck 6b, the arm 5b is then contracted to convey out the wafer 8 to the chamber 3b.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a 1' conductor wafer (hereinafter referred to as wafer) used in a 1' and conductor device manufacturing apparatus such as LSI (large scale integrated circuit). The present invention relates to an automatic transfer device, and particularly relates to a wafer transfer device that suctions and transfers only a silicon wafer between a reaction chamber and an antechamber (preliminary chamber) in a short period of time.

[Conventional technology] The progress and development of LSI technology is extremely rapid, and there are already 1
LSIs are being manufactured using fine patterns of micrometers or less. In order to manufacture such submicron-level LSIs, a high-performance manufacturing process with better controllability that is less affected by uncertain factors is, of course, required.

Examples of this include lower process temperatures and higher selectivity processes. 13. Lowering the process temperature is necessary to suppress re-diffusion of impurities within the conductor and to achieve accurate impurity distribution.

In particular, lowering the process temperature is necessary to suppress grain growth in various thin films (i-conductors, metals, and insulators) used in LSIs, and also to suppress grain growth in the thin films of the substrate crystal and its thin films and between the thin films. It is also effective in suppressing interfacial reactions.・On the other hand, for etching or thin film formation for fine pattern formation,
High selectivity due to differences in materials is essential.

The most important requirement for achieving low process temperatures and a highly selective process is that unnecessary gas components other than those necessary for the reaction are almost completely removed from the atmosphere of the reaction chamber in which the process proceeds. be.

In other words, the ultra-clean process is the ultra-fine LS
This is essential for realizing the low temperature process and high selectivity process essential for I production.

To explain the importance of clean process with a few examples: ■Silicon epitaxial growth 5IH7→St +2H2・・・・・・・・・(1)S
I H2C12+H2→St +2HCl+H・・・・
...(2) For example, silane (S) is used for epitaxial growth of silicon.
iH2) (formula (1)) and dichlorosilane (SI
H2C12) by a hydrogen reduction reaction (formula (2)).

However, oxygen (0'2) and moisture (H2O) are present in the reaction atmosphere.
), the silicon substrate surface is continuously oxidized and a thin 5I02 film is formed on the surface. High temperature is required to remove this 5I02 film by evaporation or etching.

A very clean reaction atmosphere ensures a clean silicon surface at all times. On a clean surface, the surface migration of the adsorbed S1 atoms occurs violently, and the surface adsorbed atoms tend to settle into the multilayer lattice sites, resulting in a high-quality epitaxial growth layer at a low temperature. That is, in a clean reaction atmosphere, it is possible to lower the process temperature.

■Tungsten selective growth 2WF6+3S+→2W+38I F/11...
(3) Selective growth of small crystals of tungsten (W) onto silicon (St), 1- or poly Sl l= using the raw material gas WF6 proceeds by a Si substrate reduction reaction.

In order for the reaction represented by formula (3) to proceed, 51-W
No oxide film or the like must exist at the interface, and of course W itself must not contain any oxide film or the like.

Both Sl and W are substances that are extremely easily oxidized.

Therefore, if O2 or H2O is included in the reaction atmosphere, the substrate reduction reaction as shown in equation (3) will not occur. At the interface between St and metal without an intervening 111 layer such as an oxide film, the 8l-8l bond is broken at an extremely low temperature due to the shielding effect of the metal, and S1 atoms are attached to the metal thin film surface along the grain boundaries of the polycrystalline metal. The substrate is diffused, and the substrate reduction reaction as shown in equation (3) continues to occur.

Naturally, surfaces other than SI, e.g.
W is not deposited on 2,81.3N4 as long as the substrate reduction reaction is used. That is, if the reaction atmosphere is clean, W is selectively deposited only at low temperatures and only at 5=t-.

As mentioned above, a clean reaction atmosphere enables the process to be carried out at a low temperature and with high selectivity.

To make the reaction atmosphere clean, transfer it to the raw material gas cylinder (or liquefied gas container: hereinafter collectively referred to as gas cylinder).
Gas supply system from 9 to the reaction chamber 9 The reaction chamber itself and gas υ1
Everything in the air system must be clean.

Listing the conditions, ■The source gas is as pure as possible.

■Gas supply system 9 Concerning the reaction chamber and exhaust system, (a) External leakage acid is extremely low, reducing air pollution! 1 (Ikoto.

(b) There is less gas released from the piping system and the reaction chamber tube wall. In other words, the materials that make up the piping system and reaction chamber themselves do not contain gas components. At the same time, the surface of the tube wall was added to the surface of the car for 1 minute, so that the adsorbed gas could be absorbed without having any altered layer.
There is no division. Furthermore, it must be equipped with equipment that ensures that the inside of the reaction chamber and gas supply piping system are not exposed to the atmosphere.

(C) There should be no dead zone where gas accumulates.

(d) Generation of particles (grains I'-) should be as small as possible. Even if an r+f movement mechanism is provided, there should be as few sliding parts as possible inside the gas supply system or reaction system.

Although some of the above conditions can be achieved through management or operation, the generation of particles in the movable system of the equipment is a problem with the configuration of the mechanical system itself in the wafer transport equipment, and its structure. becomes important.

In this case, what is particularly important is the wafer transport mechanism until the wafer is carried into the reaction chamber, and this includes a mechanism that supports or holds the wafer.

[Problem to be solved] Conventional wafer holding mechanisms include mechanisms that suck and hold wafers using vacuum chucks, as well as mechanical mechanisms such as wafer holders and gripping arms that hold wafers through their edges. I am holding it.

In particular, when carrying a wafer from the preliminary chamber to the processing chamber of a CVI) device or sputtering device,
This is carried out from the preliminary chamber to the processing chamber via a conveyance mechanism such as a belt conveyance mechanism, and these mechanisms include many moving parts.

As shown in the top and side views of FIGS. 10(a) and 10(b), this type of device has a vacuum chamber 1 in a preliminary chamber 100.
01 continues, and a gate valve 103 is provided in each chamber. Then, the wafer lO6 is transferred to the conveyor belt 104
From the t-equipment chamber 100, through the vacuum chamber IO1, to the processing chamber 1.
Transported to 07. In addition, 105 is the gate valve 1
A cylinder for operating 03.

In the conventional wafer transport mechanism that transports wafers from the preliminary chamber to the processing chamber, there are many mechanical I'lJ moving parts, and in particular, in the case of a vacuum suction mechanism, the suction mechanism is Due to the negative pressure, the air flow has an adverse effect on particle generation.

Therefore, the amount of particles generated inevitably increases, and it is difficult to limit this to a predetermined amount or less.

In addition, vacuum chucks cannot be used in evaporation, CV [), plasma etching, soching equipment, reactive ion etching equipment, etc., which perform processing at low pressures where vacuum chucks cannot be used. /X In many cases, a mechanical mechanism such as a wafer holder or gripping arm is used as the holding mechanism.
They tend to have more moving parts.

Therefore, it can be said that at present it is difficult to realize a low temperature process or a high selectivity process as described in +liJ.

``Invention 1'' This invention solves the problems of the prior art, and is capable of holding and transporting wafers without generating almost any particles in a mechanism for transporting wafers. In particular, it can be used even under normal pressure or reduced pressure.
It is an object of the present invention to provide a wafer transfer device that is capable of IJ and is suitable for lowering the process temperature in the manufacturing process of L conductors.

[L stage for solving the problem] Means in the wafer transfer apparatus of the present invention to achieve such an object are installed in a processing chamber having a susceptor, a pre-chamber, and a pre-chamber. It is equipped with an arm that moves to the top of the susceptor in the processing chamber, and an electrostatic chuck that has a plurality of electrodes that attracts and holds the wafer. It is called transportation.

[Operations] With this configuration, wafers can be transferred from the preliminary chamber to processing chambers such as reaction chambers simply by controlling the movement of the arm, and the wafers can be held and removed by electrical control. Because the wafer can be transported freely, and the transport mechanism is simple, external leakage and gas released from the inside of the device can be greatly reduced, making a clean process possible and eliminating the need for moving parts. is small (
This makes it possible to limit the generation of particles to a smaller number, and to realize a wafer transfer device suitable for lowering the process temperature and realizing a highly selective process.

In addition, since it uses an electrostatic chuck, it can be used under normal pressure or low pressure.
It can also be used under vacuum.

[Embodiment] An embodiment of the wafer transfer apparatus of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view of the wafer transfer device of the present invention applied to a CVD device, FIG. 2(a) is a sectional view of its electrostatic chuck portion, and FIG. FIG. 3(a), a cross-sectional view of a specific example of the electrostatic adsorption chuck section, is a schematic cross-sectional view along the line I-I in FIG. 3(b) of the electrode section of the electrostatic chuck in the wafer transfer device of the present invention. , Figure 3 (b
) is its β-plane view. Further, FIG. 4(a) is a cross-sectional view of a state in which a wafer is attracted to the electrostatic chuck electrode portion of FIG. 3(a), and FIG. 4(b) is an equivalent circuit diagram thereof. In addition, the same parts in these figures and subsequent figures are indicated by the same symbols.

In FIG. 1, 1 is a CVl) apparatus, which includes a reaction chamber 2, front chambers 3a + 3b arranged on both sides thereof,
The front chamber 3a and the preliminary chamber 4a are the side into which wafers are loaded, and the front chamber 3b is the front chamber 3b.

The preliminary chamber 4b is the side from which processed wafers are taken out.

Although not shown, there is a p-room 4a * 4
b are each provided with a mechanism for automatically feeding and taking out wafers.

Further, in this embodiment, the preliminary chamber is divided into two stages, and the preliminary chamber 3a + 3b is provided as the first preliminary chamber, and the preliminary chambers 4a and 4b are provided as the second preliminary chamber to adjust the degree of vacuum. ing. However, there is no problem even if these preliminary chambers are one stage (only the front chamber 3a or 3b).

Now, the reaction chamber 2 is made of A, l! coated with SUS (stainless steel) whose inner surface has been polished (including chemical treatment) or coated with T1N or the like. The chamber 201 is equipped with a gas introduction pipe 202 (for example, a
Gases necessary for the reaction are introduced from the reactor (US318L).

Furthermore, a baffle plate 203 is provided on the front surface of the gas introduction pipe 202 to offset the speed of the introduced gas in the straight direction and to equalize the flow of the gas.

Reference numeral 204 is a slit plate in which narrow slits are provided in the direction toward the center, or holes on a cylinder are provided two-dimensionally in a lattice rod. It constitutes the blowing surface of the reaction gas inward.

A susceptor 205 is provided below this blowing surface, and the susceptor 205 is a table made of a high melting point metal such as Mo, W, Ta, etc. coated with TIN or the like, or carbon coated with SiC, etc. 8 will be installed. A heating device 206 is installed inside the susceptor 205 to heat the susceptor 205.

Here, in order to electronically control the heating of the wafer 8, a heating device in which plasma torches are arranged in multiple stages in an axially symmetrical concentric cylindrical shape is excellent.
A gas such as Ar + N2 is sealed between the two under reduced pressure.

On the other hand, 6a is an electrostatic chuck section supported on the distal end side of the transfer arm 5a, and 10a is the electrostatic chuck. The figure shows a state in which the wafer 8 is attracted to the electrostatic chuck 10a.

Further, the transfer arm 5a is a horizontal arm of a frog-leg transfer machine whose other end is fixed to a support 7a arranged in the front chamber 3a, and moves back and forth between the front chamber 3a and the susceptor 205 of the reaction chamber 2. . Note that the transfer arm 5a may be composed of a magnetic ring, an air cylinder, or the like.

Here, the reason why the frog leg transport mechanism is used is that the transport mechanism part can be made smaller and, for example, CVD reaction chambers are provided on both sides of the front chamber, so that the support 7a of the frog leg transport mechanism can be rotated. This allows the frog leg transport mechanism to be directed toward the desired chamber, which has the advantage of allowing wafers to be selectively transported or unloaded to both chambers. Furthermore, if a front chamber is provided in a straight line between the preliminary chamber and the chamber, and its support 7a is made rotatable, the wafer can be similarly picked up from the preliminary chamber side, reversed, and transferred to the chamber side. Even in such a case, the entire device can be made compact.

Now, the front chamber 3b is also provided with a similar frog-leg transfer mechanism-type transfer arm 5b, an electrostatic chuck section 6b, its electrostatic chuck 10b, and a support f'47b in a symmetrical relationship. In addition, in the figure, the electrostatic chuck 10b
A processed wafer 8 is attracted to the wafer 8 .

By the way, the transfer arms 5a and 5b respectively serve as a reaction chamber (processing chamber) and a front chamber (
The electrostatic chuck 6a v6b is one of the specific examples of the arm that moves between the first preparatory chamber and the first preliminary chamber), and the electrostatic chuck 6a v6b is one of the specific examples of the electrostatic chuck that has a plurality of electrodes that attract and hold a wafer.
It is one. Therefore, in this example, one on each side of the reaction chamber 2.

Two wafer transfer devices are arranged.

Now, 221 and 223 are exhaust pipes that exhaust the chamber 201, and these exhaust pipes 221 and 223 are as follows.
The exhaust may be operated independently, or may be connected in the middle to be exhausted by one pump.

Furthermore, 224, 226, 227, and 228, 229 are gate valves, respectively, and the front chamber and preliminary chamber are all evacuated by a vacuum pump.

Here, to explain the operation of this device, the gas introduction valve 202 is closed, the gate valve 224,
When 225 is closed, the inside of chamber 201 is in a high vacuum state.

In this one condition, open the gate valve 224 and open the preliminary chamber 4a.
The wafer 8 carried into the front chamber 3a from the electrostatic chuck 6a
is absorbed and picked up. Next, the transfer arm 5a is extended, and the adsorbed wafer 8 is transferred from the front chamber 3a to the reaction chamber 2, positioned on the susceptor 205, L, and the wafer 8 is dropped under its own weight, or is electrostatically adsorbed to the susceptor 205 side. and installed on the susceptor 205.

Next, the transport arm 5a is contracted and the electrostatic chuck 6a is returned to the front chamber 3a. After the electrostatic chuck 6a moves to the front chamber, close the gate valve 224 and immediately open the gas inlet 2.
The valve 02 is opened to blow raw material gas onto the surface of the wafer 8 placed in the shape of a susceptor 205 to grow a thin film.

The type of gas is, for example, H2 for polysilicon growth.
+SI Hq, H2+Si 2 H6, etc., and for nitride film growth, H2+SI Hq +NHa, etc. are used. Note that the raw material gas will be changed depending on the type of thin film desired to be deposited.

When the growth of a predetermined thin film is completed, the gas inlet 202
After closing the valve and evacuating the chamber 201 to a high vacuum, the gate valve 225 is opened, the transfer arm 5b is extended from the front chamber 3b to the reaction chamber 2, and the electrostatic chuck 6b is moved onto the susceptor 205. Then, the processed wafer 8 is sucked onto the susceptor 205 and picked up. Then, the transfer arm 5b is reduced and the processed wafer 8 is transferred to the front chamber 3.
Transport to b.

The wafer thus carried out to the front chamber 3b is sent out from the front chamber 3b to the preliminary chamber 4b and taken out of the apparatus.

Next, a mechanism for bringing the electrostatic chuck close to the wafer surface and suctioning and holding the wafer will be described.

As shown in FIG. 2(a), the electrostatic chuck 10a of the electrostatic chuck section 6a has an electrostatic chuck electrode section 121, and is attached to the tip of the transfer arm 5a. Similarly, the electrostatic chuck 10b of the electrostatic chuck electrode section 6b also has an electrostatic chuck electrode section 121, which is attached to the tip of the transport arm 5b.

Since the electrostatic chuck section 6a and the electrostatic chuck section 6b have similar configurations, the electrostatic chuck 6a will be used as a representative explanation of the electrostatic chuck 6b, and the following explanation will be about the electrostatic chuck 6b. will be omitted.

The electrostatic chuck section 6a has an n-shaped housing 124, and the housing 124 is fixed to the tip of the transfer arm 5a (not shown in the figure). Reference numeral 125 denotes an introduction pipe for introducing gas, etc., which is attached to the transport arm 5a, and is connected to the housing 12 in the same manner as the transport arm 5a.
4, and supports this electrostatic chuck section 6a together with the transport arm 5a.

The electrostatic chuck electrode section 121 is shown in FIG. 3(a).

As shown in (b), it has a shape that is divided into two parts in the direction perpendicular to the plane of the paper, and is attached to a vertically movable metal disc 123 housed inside a housing 124 via an insulating spacer 122. ing. 126 is the housing 124
A cylindrical bellows 129 is attached below the bearing disk.
The vertically movable disk 123 is vertically supported by 29, and a movable support rod 131 is installed in the center thereof.

The movable support rod 131 passes through the sliding bearing portion 126a of the bearing disc 126.

Here, the insulating spacer 122 is inserted to provide a dielectric strength between the drive unit (on the vertically movable disk 123 side) and the voltage applied to the electrostatic chuck electrode unit 121. It is something.

Now, a metal back plate disk 128 is provided on the upper part of the bearing disk 126, and the other end of the movable support rod 131 is fixed to the center of the back plate disk 128. The back plate disc 128 and the bearing disc 126 are coupled via a cylindrical bellows 130.

Here, each of these bellows 130 and 129 has an upper space 132 formed inside thereof.
and the lower space 133 are kept in a sealed state, the upper space 132 communicates with the introduction hole 127, and the F section space 1
33 is filled with air at almost atmospheric pressure. On the other hand, each of the arms 5a and 5b is hollow, and this hollow portion is connected to the introduction hole 127, and air or nitrogen gas is supplied to the urban area 132 and the door communicating therewith through this hollow portion. The gas is introduced into the subspace 133 and exhausted from there. Further, wiring for the electrostatic chuck is provided inside this hollow portion.

That is, the 16th part space 132 and the 1st part space 133 are airtight spaces surrounded by bellows 129, 130, and move according to the air supplied or discharged from the introduction hole 127. The movable support rod 13 is maintained while the support rod 131, the bearing disk 126, and the L drive disk 126 are kept airtight.
1 is configured to move up and down. Note that it is also effective to provide an O ring in order to make the airtightness more complete.

Next, the vertical movement operation of the electrostatic chuck will be explained.

■When raising the electrostatic chuck.

Relatively high pressure air is supplied to the upper space 132 through the introduction hole 127 communicating with the upper space 132 .

For example, by applying pneumatic pressure (air or nitrogen gas) of about 2 kg/cI/ to 8 kg/c♂, the bellows 130 on the L side is expanded, and the bellows 129 on the t' side is expanded.
is compressed, the vertically movable disk 123 rises L as shown in the figure, and the electrostatic charger 10a (10b) moves into the housing 12.
It is stored inside 4.

■When dropping an electrostatic chuck.

- 1; High H- air is discharged from the introduction hole 127 communicating with the interspace part 132, and the pressure in the space 132 is reduced to negative rr.
:<J:c empty state or reduced pressure state or atmospheric pressure) When the bellows 130 contracts and the bellows 129 extends, the vertically movable disk 123 returns to the return direction and descends. lowers further), and the electrostatic chuck 10a protrudes from the inside of the housing 124.

By adopting a vertical movement mechanism using such a bellows, the movement mechanism becomes simple, there is less air leakage, and this contributes to suppressing the generation of particles.

Here, as the material of the bellows 129, 130, stainless steel, aluminum alloy, etc. are usually used, and especially when the weight of the electrostatic chuck is as light as possible, aluminum alloy is excellent.

By the way, when the electrostatic chuck is transported by a floral lug type transport mechanism, it is preferable that the support of the electrostatic chuck and the gas introduction hole are separated, and a flexible tube is used for the gas introduction hole.

On the other hand, the example in FIG. 2(a) shows a case where the gas introduction hole and the support for the electrostatic chuck (vertical moving disk 123) are used in common, but the position of the electrostatic chuck cannot be moved. Alternatively, when conveyance is performed using an air cylinder or a magnetic cylinder, such a cylinder is easy to use.

By the way, if the vertical movement is in the range of about 5m+s to 15+am, the above-mentioned vertical movement mechanism can be made with a total thickness of about 40mm, and the diameter of the electrode etc. should be set according to the wafer to be sucked. You can decide based on the size.

FIG. 2(b) shows another specific example of the electrostatic chuck vertical movement mechanism, in which the electrostatic chuck electrode parts 151, 151 are divided into two parts: 1. Vertical motion insulation disc 15
It is fixed to 2. Note that this upper dynamic insulating disc 152
is made of an insulating material such as molded polyimide or ceramics.

Reference numeral 153 denotes a movable support rod, which is supported by the base plate 154 via a spring 158 through iW.

The base plate 154 is fixed to the distal ends of the arms 5a + 5b of the frog leg transport mechanism, and plays the roles of the housing 124, the bearing disc 126, and the back plate disc 128 in FIG. 2(a). It is used for both purposes. Also, springs 158, 157, 158
is a spring made of a shape memory alloy such as Tl-N1 or Ti-Ni-Cu.

Here, these spring wire diameters are such that the spring 158 provided at the center is larger than the spring 158 provided at the periphery.
It is set thicker than 56 or 157. Moving support rod 15
3 slides through the through hole of the sliding bearing part 154a at the center of the fixed base plate 154, but an O-ring or a bearing may be introduced to make this sliding smoother.

The shape memory alloy used in FIG. 2(b) has the property of rapidly elongating from a certain temperature (for example, 70° C. to 80° C.) when the temperature is increased by passing an electric current through the spring, for example. On the other hand, the springs provided on the periphery are usually provided at three axially symmetrical points.

FIG. 2(b) shows a spring 156 provided around the periphery.
157 and no current is applied to the spring 158, the electrostatic chuck electrode portion 15
1 is moving downward. In this state, if the current flowing through the springs 158, 157, etc. is cut off, the temperature of the springs 156, 157, etc. decreases and they begin to move upward. However, since this takes time and the response speed is slow, the current is passed through the spring 158 at the same time as the current flowing through the springs 158, 157, etc. is turned off, or a little earlier than that.

Since the wire diameter of the spring 158 is set thick,
If the temperature exceeds a certain level and begins to stretch, the spring 156
．． Even if the temperature of the insulating disk 157 has not completely decreased, the vertically movable insulating disk 162 moves upward.

Due to this, the response speed to the 1-F movement of the electrostatic chuck is significantly improved.

The wire diameter of a shape memory alloy spring such as T I-N 1 is for 2s, 3n wafers, for example, if the wire diameter of spring 156.157 is 1.0ma+φ and the spring 158 is 1.8mmφ, etc. Well, 4#~
For 6# wafer, for example, spring 158.15
It is preferable that the wire diameter of the spring 158 is 1.2++usφ, and the spring 158 is 2.0ma+φ.

In addition, the current value to be passed also changes depending on the specific heat, resistivity, wire diameter, etc. of the material, but if the wire diameter is as described above, 5A~
It works well with BOA.

In addition, for example, when leaving the spring along the outer periphery in Figure 2(b) and arranging the magnet and electromagnet to face each other at the center with a predetermined gap in between, when no current flows through the electromagnet, the electrostatic chuck electrode 151's own weight causes the spring to stretch and move downward, and when current is applied to the electromagnet, the magnet and electromagnet attract each other,
It is also possible to adopt a configuration in which the electrostatic chuck moves in the "Y" direction.

In such a case, for example, a spring 156.
157 is provided, and a shaft passing through the base plate 154 is embedded in the vertically movable insulating nine disc 152, which can be easily realized.

By the way, the electrostatic chuck electrode portion shown in FIGS. 2(a) and 2(b) can be moved not only downward, but also in any direction, whether facing up or facing upward.

Next, details of the electrode portion of the electrostatic chuck will be explained.

In addition, in FIG. 1, the electrostatic chucks 10a and 10b are
Since they have the same configuration, in the following description, the electrostatic chuck 10 will be explained, and its electrode portion will be referred to as an electrostatic chuck electrode portion 17.

Now, as shown in FIGS. 3(a) and 3(b), the electrode part 17 of the electrostatic chuck IO for wafer suction is a semicircular cane with semicircular recesses 11a and 12a provided inside the back surface, respectively. It is formed by first and second electrodes 11 and 12 made of a conductor such as metal.

By the way, when automatically transporting wafers, there are overwhelmingly many cases where it is required to suck up and transport the wafers from the front side. Therefore, the electrode section 17 is attached as an electrostatic chuck in a suspended state on a wafer transfer device so that its suction surface side becomes a part of the chuck.

Here, these first. The second electrode 11.12 is the insulating film 1
3.14, and are arranged at predetermined intervals. This gap may be left as a void, or an insulator may be inserted depending on the structure. The selection may be determined based on the overall structure of the electrostatic chuck 10.

1st. As shown in FIG. 3(a), the second electrodes 11 and 12 have a substantially diagonal outer periphery with a radius R and are recessed inside with a width W remaining. This serves as a suction portion 15.18 for a semiconductor wafer. An insulating film 15a is formed on the surface of each of the suction parts 15.18 as a part of the insulating film 13.14.

18a is provided as a coated layer, and the film thickness of these insulating films 15 at l 6 a is determined based on the suction force of the wafer and the like. The thickness of the insulating films 13 and 14 other than this portion is determined in consideration of the fact that this electrode portion has sufficient breakdown voltage when it comes into contact with other metal portions.

Next, the operation of the electrostatic chuck electrode section 17 to attract a wafer will be described. As shown in FIG. 4(a), the wafer 8 is attracted to the attraction section 15.16 at its peripheral portion. When the wafer 8 is automatically transported, the electrostatic chuck 10 sucks it up from its front side and holds it. Then, it is transported from the front chamber 3a, which is the transport source, to the reaction chamber 2, which is the transport destination. In this respect, the situation is different from a simple vacuum chuck, in which the wafer is normally attracted and fixed onto the upper surface from the back side. Note that 18 is a voltage source (its voltage value V) of this electrostatic adsorption chuck.

Now, normally, an IC (integrated circuit) is located in an area of about several inches from the outside in the peripheral part of the disc wafer 8.

Devices such as LSI (large scale integrated circuit) are not provided. Therefore, the periphery of the wafer 8 is attracted by the electrostatic chuck electrode section 17.

No deterioration in LSI performance at all. FIG. 4(a) shows a case where the outer diameter of the electrostatic chuck IO is almost equal to the outer diameter of the wafer 8.

In order to drop the wafer 8 by its own weight, this suction part width W is
is usually set to a value of about 0.1 ww+ to 3 ww+, particularly preferably 0.2. It is preferable to be in a range of about +u+ to l+m. Note that the narrower the width W, the less contamination and damage to the wafer 8. Of course, the electrostatic chuck electrode part 1
Needless to say, sufficient consideration must be given to the contact pressure when bringing the wafer 7 into contact with the wafer 8, and the pressure must be set to a value that will prevent defects such as dislocations from entering the wafer 8.

The diameter (2R) of the electrostatic chuck electrode portion 17 is slightly smaller than the diameter of the wafer 8 (although it may be slightly smaller, but the electrostatic chuck electrode portion 17 must be accurately positioned directly above the wafer 8). In order to reliably attract the wafer 8, it is better to make the diameter of the wafer 8 almost equal to or slightly larger than the diameter (2R) formed by the electrodes 11 and 12 of the electrostatic chuck electrode section 17.

There are various types of wafers used in the semiconductor manufacturing process. For example, in terms of materials, Si, Ge
, GaAs, InP, etc. are used. The resistivity value ρ of the wafer also depends on the material, but it is 108Ω・cIB.
It varies within a range of about 10-3Ω*cm. Further, an insulating film such as oxidation film may be provided on the wafer surface to a thickness of about 1 μm or more, and a resist film may be further attached to the -[-.

The one-electron relaxation time τd of the wafer is τd=ρε ・・・・・・・・・・・・−−−−−(
4) is given by ρ is resistivity and ε is dielectric constant.

Here, ρ: I X I Q8Ω*cm”1X10-
Assuming 3Ω・C■, the one-electrode relaxation time rd given by equation (4) is lXl0−”see ~lXl0″″l5s
The value is about ec. In other words, if the material (wafer) has a resistivity within this range, it can be treated as a conductor in terms of direct current.

Therefore, if the state in which the wafer 8 is attracted to the electrodes 11 and 12 of the electrostatic chuck electrode section 17 is expressed in terms of an electrical circuit as shown in FIG.
A capacitor 19.20 formed by 5.18 is connected in series with the voltage source 18.

The direct current of capacitor C is is given by .

However, δ and S are the insulating film thickness of the adsorption part and the area of the Pt adsorption part. εI is the dielectric constant of the insulating film.

The value of capacitor C depends on the thickness of the oxide film on wafer L.

It varies to some extent depending on the resist thickness, wafer resistivity, etc.

From the radius (R) in Figure 3(b), the area is Habo, S Aya π
RW - It is given by (8). However, this is the case where R>>W and R>>D. Of course, the relationship between R and D is not necessarily limited to the above relationship. The force F acting on the electrodes of the capacitor can be obtained as follows. Here, ■ is the power supply voltage. In FIG. 4(b), the voltage applied to one capacitor is V/2. Therefore, the force f (New
ton) is as follows.

On the other hand, the quality mm and weight f of the wafer are as follows: M=ρ0πR2t (9)
f=MG=ρ0πR2tG (10)
However, ρO: specific gravity, R=radius of the wafer, 1=thickness of the wafer, and G=gravitational acceleration (9.8 m/5ec2).

Note that the mass M and weight f of the SI wafer are shown in the table of FIG. The specific gravity ρO of Sl is 2°328g/ama=2.32
8XIO3kg/m3.

The voltage V required to absorb the weight of the wafer given by equation (1G) is obtained from equations (8) and (10). εχ is the dielectric constant of the insulating film. When the wafer is not completely adhered to the insulating film and there is a gap χ, the voltage V required to suck the wafer is as follows.

For example, 2R=50. ,,W=5. ,,I)=10. ,
.

If δ=10 μml eχ=2.5, the voltage V required to pick up a wafer of M=2°36g (f=2.31xlO-2N) is calculated from equation (11) as 2
It becomes 4V. Of course, it is not actually possible to create a barking state in which the electrostatic chuck 10 is in complete contact with the electrostatic chuck 10, so a voltage of several hundred volts, which is larger than the above value, is required.

Polyimide resin is used for the insulating film of the electrode part, and the electrode 11.1
According to an example of an electrostatic chuck for 2" wafers using aluminum (AI) as the conductor of 2" (2R=50mm,
I)=lOmm, δ=10 u m vεχ=2.
5), suction part t51. If the width W of lea is 5■■,
The wafer 8 can be easily attracted and transported at about 500V. However, since the wafer surface is normally flat on the order of several tens of eights, once the wafer 8 is attracted to the electrostatic chuck electrode section 17, even if the voltage is returned to Ov, the wafer 8 remains attracted and the wafer 8 itself It cannot be separated from the electrostatic chuck 10 due to its weight.

The problem with wafer transport using the electrostatic chuck electrode section 17 lies in the detachment of the wafer 8 rather than the adsorption of the wafer 8. Although it depends on the outer diameter of the wafer 8, in the above-mentioned electrostatic chuck for 2" wafers, if the suction part width W is set to 5+ui or more, the wafer 8 may be suctioned, but the wafer cannot be held by electrical operation alone. 8 cannot be detached by its own weight (detachment by falling). However, it is not preferable to provide a special detachment mechanism because it has the potential to increase the generation of particles.

It is preferable that the wafer be adsorbed and the wafer removed by its own weight using all electrical operations.

The width W of the suction portion 15a and IE3a in each electrode 11° 12 of the electrostatic chuck electrode portion 17 described above is set to 0.2 mm to 1.
If the setting is about m+intestine, the wafer adsorption will be 500~
It can be done by applying a voltage of 700V, and the applied voltage is 200 to 300V.
If the voltage is lowered to about V or less, the wafer will separate from the electrostatic chuck 10 due to its own weight. That is, when attempting to hold a wafer by electrostatic adsorption in order to transport the wafer, the adsorption part width W is set to 1 so that the wafer can fall under its own weight according to the weight of the wafer.
- It is necessary to keep it narrow. Alternatively, the suction portion width W may be set to about 1 to 2111 mm, and cut portions may be provided at important points in the circumferential direction to make the effective suction portion area smaller than a predetermined value.

Therefore, the width of the suction part is basically related to its total suction area.

In this way, the wafer can be sucked up by adsorption on the surface within about 1IIm of the wafer periphery, and the wafer can be held on the side of the electrostatic chuck 10 and transported.

Therefore, there is almost no damage or contamination on the wafer surface, especially on the IC and LSI device parts, and an ideal wafer transfer apparatus can be provided.

Now, to explain in detail the operation of transporting a wafer by such an electrostatic chuck electrode section, the wafer 8 is carried to the front chamber 3a by a belt transport mechanism or other handling mechanism, and the susceptor in the front chamber 3a is moved. When placed on the
As shown in FIG. 2(a), the wafer 8 placed on the susceptor is exposed to the upper F motive plate 123 by exhausting high-pressure air from the introduction hole 127 communicating with the upper space 132 formed by the bellows 130. The electrostatic chuck 10 descends
is in contact with the periphery of the wafer 8. In this state, a predetermined value or more is applied to the electrodes 11 and 12 of the electrostatic chuck 10.

For example, a voltage of 500 V or more is applied and the wafer 8 is attracted. The introduction hole 12 communicates with the upper space 132.
When a predetermined amount of high-pressure air is introduced into the upper space 132 from the wafer 7, the vertically movable disk 123 rises a little, and the electrostatic chuck 6a leaves the upper part of the susceptor while holding the wafer 8.

In this state, the gate valve 224 between the reaction chamber 2
is driven to release, the frog leg transport mechanism performs an extension operation, moves the arm 5a forward toward the reaction chamber 2, and transports the wafer 8 into the reaction chamber 2.

Then, the forward movement of the arm 5a is stopped at a predetermined position on the susceptor 205 of the reaction chamber 2, and the high-pressure air inside the bellows 130 of the electrostatic chuck 6 is exhausted to create a negative pressure, and the electrostatic chuck 10 is lowered. , the wafer 8 is stopped at or very close to contacting the susceptor 205 of the reaction chamber 2. Here, electrode 1 of electrostatic chuck 10
When the voltage of 1.12 is lowered by a predetermined amount, the wafer 8 is detached by its own weight.

Thereafter, the frog leg transport mechanism performs a contraction operation to retreat the arm 5a from the reaction chamber 2, and the gate valve 224
is closed and the wafer undergoes the reaction process described above.

In order to keep the wafer surface clean, the wafer 8 must be held at any angle with respect to the horizontal plane so that the surface of the wafer is, for example, vertical or facing downward, in order to prevent particles from being adsorbed to the surface in the reaction chamber 2. It is desirable to be able to hold the

Here, when the predetermined processing is completed, the arm 5b is operated in substantially the opposite manner to that described above, and the processed wafer 8 is taken out from the reaction chamber 2 into the front chamber 3b.

Next, a specific example of another structure of the electrostatic chuck electrode section is shown in FIG. 5(a).

This electrostatic chuck lO has suction portions 15 and 16 provided at the inclined tip in order to reduce the weight of the electrode portion ff1 (fl) and to more accurately align the wafer and the electrostatic chuck electrode portion. It is.

Similarly, in the electrostatic chuck electrode section 30 shown in FIG. 5(b), the width of the adsorption section 31 al 31b in each electrode is about 1 mm to 2 layers, especially in the case of a 2# wafer. As shown in the enlarged view of the suction part 31a shown in FIG. (Similarly on the suction part 31b side, this is not shown)
The recess 32 inside each electrode has a substantially semicircular shape.

FIG. 6(a) shows still another specific example, in which the suction portion 33 of each electrode of the electrostatic chuck electrode portion 33 is shown.
a and 33b have a corrugated cross section, and each convex portion has a diameter of 0.2
It is about 1 mm from ra-, and FIG. 6(b) shows an example in which the shape of the suction part has one relatively sharp waveform.

Further, FIG. 6(C) shows an electrode part structure for adsorbing not the surface of the wafer 8 but the edge portion of the outer periphery of the wafer 8. FIG. The suction portion 34a of each electrode of the electrostatic chuck electrode portion 34 has a structure that causes the least amount of contamination on the wafer surface.

34b has a gentle slope.

In any case, it is an electrostatic chuck that can electrically adsorb a wafer and detach it electrically in relation to its own weight, and has at least two or more parts around the wafer that do not affect the device. Of course, any structure may be used as long as the wafer is attracted by a suction section provided with a thin insulating film by applying a DC voltage to the divided electrodes.

So far, we have described a mechanism that applies a voltage to the wafer to attract it, and a mechanism that releases the wafer from the electrostatic chuck by its own weight by returning the voltage to a predetermined voltage or lower or OV.

By the way, if it is sufficient to simply place the wafer in an L-oriented state by adsorbing the front side (two sides) of the wafer, the applied voltage may be returned to a predetermined voltage or lower or Ov at a necessary location.

For example, the wafer is attracted to an electrostatic chuck, transported to a predetermined location in the reaction chamber 2, placed, and moved until it lightly touches or almost touches the substrate (hereinafter collectively referred to as susceptor), and then applies the applied voltage. By returning the wafer to OV, the wafer is separated from the electrostatic chuck and placed in a predetermined location such as a susceptor.

On the other hand, in plasma processes such as reactive ion etching (RIE) equipment, a susceptor structure in which the electrode is covered with an insulator is often used to suppress contamination from the susceptor (electrode) on which the wafer is placed. . Moreover, it is often necessary to control the wafer temperature by closely contacting the wafer with the susceptor.

Furthermore, it is also required that the wafer be installed vertically or facing downwards. In such a case,
Since an electrostatic chuck attracts a wafer using electrostatic force, the electrostatic chuck can be rotated and moved in any direction such as vertically or horizontally while the wafer is being attracted.

FIG. 7 shows an example of vertical support in such a case, in which the wafer 8 is placed on the susceptor 21 which is vertically grounded.
It is an explanatory diagram when passing and setting the receiver.

First, the wafer 8 attracted to the electrostatic chuck electrode portion 35 is brought into contact with the susceptor 21 covered with the insulator 22 . In this state, voltage Vs is applied to the susceptor 21, and voltage V applied to both electrodes 11 and 12 of the electrostatic chuck electrode section 35 is reduced to O.
Make it V. If we express the state at that time using an electric circuit, the 8th
It will look like the picture.

19.20 is the electrode 11.12 of the electrode part 35 and the wafer 8
The capacitor C924 formed between the susceptor 2 and
1 and wafer 8 form a capacitor CO therebetween.

The voltage vO applied to CO is: The wafer 8 is brought into close contact with the susceptor 211 by the electrostatic force of this voltage. After this happens, electrostatic chuck 3
If you release 5 from above susceptor 21, Unino 18 will become susceptor 2.
It comes into close contact with a predetermined location of 1.

In FIG. 7, the negative electrode side of the voltage source V is grounded, but the positive electrode side may be grounded. Also, the positive of Vs,
It doesn't matter whether it's negative or not. You can decide whichever is more convenient for the overall system.

Next, referring to the material and dimensions of the electrostatic chuck electrode part, in Figs. 3(a) and (b), the thickness h of the electrode 11°12
It is preferable that the electrostatic chuck electrode part 17 be thick (as long as the mechanical precision allows, so as not to become too thick or too heavy). It will be done.

Since the electrode material does not pass current, any conductor is sufficient. Any conductive material may be used as long as it can be easily electrically contacted with a wire or the like for applying voltage.

For example, metals such as aluminum and stainless steel, and semiconductors such as silicon to which impurities are added to a certain high concentration are used, and the material may be determined based on the environmental atmosphere of the device to be used.

In addition, for the insulating film applied to the suction part, it is best to choose an insulating material that does not contaminate the silicon wafer, does not emit much gas in a vacuum, and has a certain degree of heat resistance: for example, imide resin such as polyimide. , fluororesin such as Teflon, etc. are selected. The thickness of the insulating film on the suction part is
It is sufficient if the thickness is sufficient to withstand pressure. As is clear from equation (II), as the insulation thickness δ increases, the voltage V, which is insufficient to attract the wafer, increases in proportion to δ.

Insulating a voltage of about 1000 to 2000 V is extremely easy if the system has a current that does not last long.

For example, if the thickness of the insulating film is set to about 10 to 50 μm,
500 for both polyimide resin and fluorine resin
Wafer suction can be sufficiently performed with a power of ~100 OV.

As explained above, the wafer transfer device of the present invention, which adsorbs the wafer and transfers the wafer by applying voltage to the coated electrodes over several meters around the wafer periphery, is capable of absorbing the wafer at high pressure, normal pressure, Can be used in either reduced pressure or vacuum atmospheres, facing upwards or downwards.

It is particularly suited for high-quality process equipment oriented to ultra-clean processes, as it can be used in either horizontal orientation (without contaminating or unduly stressing the wafer), and at the same time Full automation of the device can also be facilitated.

Incidentally, in the embodiment, the moving mechanism includes a mechanism for moving the electrostatic chuck up and down and an arm for moving it in a certain direction, but it is not necessarily necessary to include a mechanism for moving the electrostatic chuck up and down.

In addition, in the embodiment, two wafer transfer devices are provided on both sides of the reaction chamber 2 to transfer the wafer 8 onto the susceptor 205 in the chamber 201 and to transfer the wafer 8 taken out from the susceptor 205. Although two different electrostatic chucks are used, only one of the wafer transfer devices is provided, and only one of the front chambers 3a * 3b is provided. Of course, wafers may be taken in and out.

In the example, the arm is driven by a frog leg transfer mechanism, and the arm is moved back and forth between the front chamber of the CVD apparatus and the reaction chamber of the CVD apparatus, and the wafer is moved from the front chamber to the reaction chamber. The mechanism may be of any configuration that allows the arm to move directly from the antechamber to the reaction chamber. Moreover, the reaction chamber is not limited to the reaction chamber of a CVD apparatus, and may of course be any other general processing chamber.

Further, in the embodiment, a bellows type mechanism is used as the mechanism for moving the electrostatic chuck up and down, but the moving mechanism is not limited to such a mechanism.

Furthermore, in the example, in addition to the wafer falling under its own weight, there is also an example where the wafer is attracted to another electrostatic chuck. Of course, various shapes can be selected depending on the side condition and shape.

[Effects of the Invention] According to the wafer transfer device of the present invention, a processing chamber having a susceptor, a preliminary chamber, an arm installed in the preliminary chamber and moving from the preliminary chamber to the upper part of the susceptor in the processing chamber, and a wafer transfer device are provided. It is equipped with an electrostatic chuck that has multiple electrodes that attract and hold the wafer.The electrostatic chuck is attached to an arm and the wafer is held and transferred by the electrostatic chuck, so the movement of the arm is simply controlled. The wafer can be transported from the preliminary chamber to a processing chamber such as a reaction chamber, and the wafer can be held and removed by electrical control.

As a result, wafers can be transported freely, and the transport mechanism is simple, so external leakage and gas released from the inside of the device can be drastically reduced, making a clean process possible. It is possible to realize a wafer transfer device that can limit occurrence to a smaller number and is suitable for lowering the process temperature and realizing a highly selective process.

In addition, since it uses an electrostatic chuck, it can be used under normal pressure or low pressure.
It can also be used in a vacuum.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of JR's main parts in which the wafer transfer device of the present invention is applied to a CVD device. Fig. 2 (a) is a cross-sectional view of the electrostatic chuck section, and Fig. 2 (b) is a cross-sectional view of the other parts. FIG. 3(a) is a cross-sectional view of the electrostatic adsorption chuck part of a specific example of the present invention, and FIG. FIG. 4(b) is a plan view thereof, FIG.
b) is its equivalent circuit diagram; FIGS. 5(a) and 5(b) are explanatory diagrams each showing an example of the shape of the electrode of the electrostatic chuck;
Figure 5(C) is an enlarged view of the suction part in Figure 5(b), and
Figures (aL (bL) and (c) are explanatory diagrams showing examples of the shapes of other electrodes of the electrostatic chuck, respectively, and Figure 7 shows the vertical wafer suction and holding when the wafer is received and transferred to a vertical susceptor. FIG. 8 is an explanatory diagram of an example shown in FIG.
2A and 2B are a plan view and a side view, respectively, centering on the preliminary chamber of the wafer transfer device. l...Wafer transfer device, 2...Reaction chamber, 3a*
3 b ”・front chamber, 4 a * 4 b ”・preparatory chamber, 5as5b... arm, 6 a q 8 b...
・Electrostatic chuck part, 7 a = 7 b... support part,
8... Wafer, 10.10a, 10b-... Electrostatic chip +
-/ri, 11...first electrode, 12...second electrode, 11a, 12a...recessed portion, 15.1B, 31a, 31b, 33ae 33b. 34a, 34b--Adsorption part, 15a, 18a--Insulating film, 17, 30, 33, 34.35--Electrostatic chuck electrode part, 18--Power supply, 19.20, 24-- capacitor. 201... Chamber, 202... Gas introduction pipe, 203... Baffle plate, 204-... Slit plate, 206... Heating device, 221.223... Exhaust pipe, 224.228, 227 ,228.229...Gate valve. Patent Applicant: Tokyo Electron Co., Ltd. Agent, Patent Attorney: Nobu Kajiyama, Patent Attorney: Fujio Yamaki Figure 2 (b) 1! :ll Iko 1 part a
Figure 12α Figure 4 (α) Figure 6 (Q) 1. - Cup (b) Figure 7

Claims (8)

[Claims] (1) A processing chamber having a susceptor, a preliminary chamber, an arm installed in the preliminary chamber and moving from the preliminary chamber to the upper part of the susceptor in the processing chamber, and a stationary station having a plurality of electrodes for sucking and holding a wafer. 1. A wafer transfer device comprising: an electrostatic chuck, the electrostatic chuck being attached to the arm, and a wafer being held and transferred by the electrostatic chuck. (2) The electrostatic chuck is attached to the tip side of the arm via a vertical movement mechanism, and each of the plurality of electrodes has a wafer attached to it when the voltage applied to the electrostatic chuck falls below a predetermined value. 2. The wafer transfer device according to claim 1, further comprising a suction portion whose surface is coated with an insulating film and which detaches the wafer. (3) The arm is composed of a frog leg transport mechanism,
The vertical movement mechanism has an airtight chamber surrounded by a bellows and a hole for introducing gas into the airtight chamber, and the suction part is activated when the voltage applied to the electrostatic chuck falls below a predetermined value. 3. The wafer transfer device according to claim 2, wherein the wafer is detached by its own weight or by being attached to another electrostatic chuck. (4) The electrostatic chuck is attached to the tip side of the arm via a vertical movement mechanism, and each of the plurality of electrodes has a wafer attached to it when the voltage applied to the electrostatic chuck falls below a predetermined value. A suction part whose surface is coated with an insulating film is provided to detach the wafer. 2. The wafer transfer device according to claim 1, wherein the wafer transfer device is formed as a protrusion having a predetermined width in order to remove the wafer when the wafer is removed. (5) the protruding portion is formed in a substantially semicircular shape corresponding to the peripheral portion of the wafer in order to adsorb the peripheral portion of the wafer;
5. The wafer transport device according to claim 4, wherein the width thereof is in the range of 0.1 mm to 2 mm. (6) The arm is composed of a frog leg transport mechanism,
The vertical movement mechanism has a shape memory alloy, and the suction part releases the suctioned wafer by its own weight when the voltage applied to the electrostatic chuck becomes less than a predetermined value, or removes the suctioned wafer from other electrostatic chucks. The wafer transfer device according to claim 2, wherein the wafer transfer device is detached by being attracted to a chuck. (7) The suction part is for suctioning the peripheral part of the wafer, and is formed as an uneven part with a predetermined width in order to detach the wafer when the voltage applied to the electrostatic chuck becomes less than a predetermined value. The wafer transport device according to claim 6, characterized in that: (8) The suction part is formed in a substantially semicircular shape corresponding to the peripheral part in order to suction the peripheral part of the wafer,
8. The wafer transfer device according to claim 7, wherein the convex portion of the uneven portion has a width in a range of 0.1 mm to 1 mm, and has a plurality of convex portions.