JPH06244143A - Treating device - Google Patents

Abstract

PURPOSE:To provide a treating device using aluminum nitride which can withstand against thermal shocks, etc., as the insulator of its temperature adjusting heater. CONSTITUTION:In the treating vessel 4 the treating container 4 of which houses a mounting table 8 provided with a chuck section 22 and cooling means 16, a temperature adjusting heater 52 which adjusts transferred cold heat is provided between the section 22 and means 16 and aluminum nitride which can withstand thermal shocks is used for the insulator of the heater 52 so that an abrupt temperature change of an object W to be treated attracted to the section 22 by suction can be absorbed without destroying the insulator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to processing equipment such as etching equipment and sputtering equipment.

[0002]

2. Description of the Related Art Generally, in a semiconductor manufacturing process, an object to be processed, for example, a semiconductor wafer, is repeatedly subjected to a sputtering process, an etching process and the like in various processing apparatuses. In this case, it is necessary to securely hold the wafer in the processing container, and in the conventional mechanical chuck method of fixing the wafer with a clamp or the like, it is necessary to press the periphery or the surface of the wafer. It is clear that this will cause For these reasons, electrostatic chucks that generate far less particles than mechanical chucks are mainly used. The adsorption principle of this electrostatic chuck is
A high DC voltage is applied to the electrodes facing the wafer via an insulating layer to generate a charge opposite to the charge of the electrodes on the electrode facing surface of the wafer, and the Coulomb force acting between them causes the wafer to move. , Is held by suction on the side of the susceptor to which the electrostatic chuck is attached.

On the lower surface of the susceptor, there is provided a cooling block provided with a coolant passage through which a coolant or the like for cooling and controlling the temperature of the wafer heated by plasma or the like to a predetermined processing temperature flows. The cold heat from now on is supplied to the wafer. Further, since the processing of the wafer is usually performed under a reduced pressure such as a vacuum, a very small amount of gas plays a heat transfer function at the interface between the wafer and the electrostatic chuck or the interface between the susceptor and the cooling block. As a result, the heat transfer efficiency is greatly reduced, and in order to compensate for this, an attempt has been made to effectively control the wafer temperature by supplying a heat transfer promoting gas to these interfaces.

[0004]

By the way, in the above-described conventional wafer cooling structure, generally, a CFC-based gas such as Fluorinert or perfluorocarbon is used as a coolant, and the temperature of the coolant itself is adjusted. By doing so, the temperature of the wafer is controlled. However, since the distance between the coolant passage and the wafer is generally long, it takes a considerable time for the temperature of the temperature-controlled coolant to affect the wafer temperature, resulting in poor thermal response. Therefore, there is an improvement in that the wafer temperature cannot be quickly controlled. In particular, since there are a plurality of bonding surfaces of members, that is, member interfaces, between the wafer and the cooling block, there is a problem that thermal response is further deteriorated.

Recently, a so-called low-temperature etching treatment method has been developed in which a wafer is kept at an ultra-low temperature of about -150 ° C. using liquid nitrogen, for example, and etching treatment is performed under reduced pressure in this state. According to this low-temperature etching process, when etching, for example, a polysilicon film or a silicon oxide film, the selection ratio with respect to the base can be increased as compared with the conventional method, and anisotropy is sufficiently secured. can do. However, even if this low temperature etching treatment is adopted in the above-mentioned structure, the above-mentioned problems occur. Therefore, the present inventors proposed a device in the previous application (Japanese Patent Application No. 4-220623) in which a temperature adjusting heater is provided between the susceptor and the cooling means.

The temperature of the wafer is controlled by controlling the amount of heat generated by this heater to adjust the cold heat supplied from the cooling means to the wafer, thereby improving the thermal response and the like, and at various different temperatures. It has become possible to process wafers. In the proposed device, the insulating material of the heater is, for example, Al ₂ O ₃ or SiC.
However, since Al ₂ O ₃ is relatively weak against thermal shock, when the wafer processing temperature is rapidly changed from −150 ° C. to + 50 ° C., the material is destroyed by thermal shock. However, there is an improvement in that the wafer wattage cannot be obtained or a high watt density cannot be obtained, and because the thermal conductivity is poor, the in-plane uniformity of the wafer temperature cannot be sufficiently secured.

Further, although SiC has better characteristics in thermal conductivity and thermal expansion coefficient than Al ₂ O ₃ , it has the drawbacks of low dielectric strength and large dielectric constant, and is currently hot. Since it can be manufactured only by the pressing method, it is very expensive and there is a problem that the cost must be increased. The present invention has been made to pay attention to the above problems and to solve them effectively. It is an object of the present invention to provide a processing apparatus using aluminum nitride, which is resistant to thermal shock and the like, as an insulator for a temperature adjusting heater.

[0008]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention has a chuck part for adsorbing and holding an object to be processed in a processing container and cooling the object to be processed in the lower part. In a processing apparatus including a mounting table having a cooling unit, a temperature at which aluminum nitride is used as an insulator between the chuck unit and the cooling unit to adjust the cold heat supplied to the object to be processed. An adjustment heater is provided.

[0009]

Since the present invention is configured as described above, the object to be processed is adsorbed and held by the chuck portion, and the cold heat from the cooling means is transferred from the temperature adjustment heater to the object to be processed. Is transmitted to the object to be processed. Therefore, by controlling the heat generation amount of the heater, the temperature of the object to be processed can be quickly controlled, and the thermal response can be improved. In this case, aluminum nitride is used as the insulator of the heater even if a thermal shock is generated by greatly changing the heating value of the heater in a short time so as to change the processing temperature of the object to be processed, so that it does not break down, Also,
In-plane uniformity of the object to be processed can be ensured.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the processing apparatus according to the present invention will be described in detail below with reference to the accompanying drawings. 1 is a cross-sectional view showing an embodiment of the processing apparatus according to the present invention, FIG. 2 is a schematic exploded view showing a mounting table of the processing apparatus shown in FIG. 1, and FIG. 3 shows a temperature adjusting heater used in the apparatus of the present invention. FIG. 4 is a plan view and FIG. 4 is a sectional view of the heater shown in FIG.

In this embodiment, a plasma etching apparatus will be described as an example of the processing apparatus. As shown in the figure, this etching apparatus 2 has a processing container 4 which is formed of a conductive material such as aluminum into a cylindrical or rectangular shape, and an insulating plate 6 of ceramic or the like is provided at the bottom of the container 4. Object to be processed, for example, semiconductor wafer W
A mounting table 8 having a substantially columnar shape for mounting thereon is accommodated. The mounting table 8 is mainly configured by a susceptor support table 10 formed of aluminum or the like in a cylindrical shape, and a susceptor 14 made of aluminum or the like that is detachably provided by bolts 12 on the susceptor support table 10.

The susceptor support 10 has a cooling means,
For example, a cooling jacket 16 is provided, and a refrigerant such as liquid nitrogen is provided in the jacket 16 as the refrigerant introducing pipe 1.
It is introduced via 8 and circulates in the jacket, and is discharged from the refrigerant discharge pipe 20 to the outside of the container. The susceptor 14 is
The central portion is formed in a disk shape having a protrusion shape, and an electrostatic chuck 22, for example, is formed as a chuck portion on the wafer mounting portion at the center thereof in an area substantially the same as the wafer area. The electrostatic chuck 22 is formed, for example, by sandwiching a conductive film 24 such as a copper foil in an insulating state between two polymer polyimide films. The conductive film 24 is a filter that cuts a high frequency on the way by a voltage supply lead 26. It is connected to the DC high voltage source 28 via 27. Therefore, by applying a high voltage to the conductive film 24, the chuck 22
The upper surface of the wafer W can be suction-held by the Coulomb force. A gas passage 30 is formed in the susceptor support 10 and the susceptor 14 for supplying a heat transfer promoting gas such as He to the back surface of the wafer W. still,
A large number of vent holes (not shown) are formed in the electrostatic chuck 22 to allow the heat transfer promoting gas to pass therethrough.

An annular focus ring 32 is arranged at the upper peripheral edge of the susceptor 14 so as to surround the wafer W. The focus ring 32 is made of an insulating material that does not attract the reactive ions, and allows the reactive ions to effectively enter only the semiconductor wafer W inside. The susceptor 14 is provided with a pipe lead 34 made of a hollow conductor that penetrates the susceptor support 10. The pipe lead 34 has a wiring 36.
Is connected to a high frequency power source 38 for generating plasma of 13.56 MHz, for example. Therefore, the susceptor 14 is configured as a lower electrode. And
A filter 40 for noise cutting and a capacitor 42 for matching are sequentially provided on the wiring 36.

Above the susceptor 14, the upper electrode 4 is grounded at a distance of about 15 to 20 mm.
4 are provided, a process gas, for example, an etching gas such as CF ₄ is supplied to the upper electrode 44 through a gas supply pipe 46, and a large number of small holes 48 formed on the electrode surface of the upper electrode 44. The etching gas is blown out into the processing space below. An exhaust pipe 50 is connected to the lower side wall of the processing container 4 so that the atmosphere inside the processing container 4 can be exhausted by an exhaust pump (not shown).

A temperature adjusting heater 52, which is a feature of the present invention, is provided between the electrostatic chuck 22 and the cooling means 16. Specifically, the heater 52 is formed into a plate shape having a thickness of about several mm, and as shown in FIGS. 3 and 4, inside the heater 52, for example, tungsten, carbon, or an Fe—Cr—Al alloy (for example, a river is used). Rare earth elements, especially La and Y, are added in trace amounts to give oxidation resistance with light (trade name) and feclaloy (trade name))
A linear or strip-shaped resistance heating element 54 made of, for example, is arranged in a meandering shape or a one-stroke writing shape. The entire resistance heating element 54 is made of sintered AlN.
It is covered with an insulator 56 made of (aluminum nitride), and when the heater 52 is attached, the internal heating element 54 can be electrically insulated from the external base side. The AlN forming the insulator 56 has a thermal conductivity about 10 times higher than that of the conventionally used ceramics such as Al ₂ O ₃ and has a high durability against thermal shock, and thus is sharp. Difficult to break even with various temperature changes. For example, regarding the coefficient of thermal expansion, Al ₂ O ₃ is 7.3 × 1.
0 ^-6 / ° C, whereas AlN is 4.5 x 10 ^-6 / ° C
And the tensile strength of Al ₂ O ₃ is 24-26k.
gf / mm ² whereas AlN is 40-50 kg
It has a high f / mm ² and is excellent in strength. Also, since AlN is an electrical insulator, heat is transferred via phonons.
From the heat conduction mechanism (as shown in FIG. 5), the heat conductivity shows a peak at room temperature or lower. Therefore, at about 100K (-173 ° C), the value becomes larger than the value at room temperature. In addition, AlN is shown in FIG.
As can be seen from the above, the thermal conductivity increases and the heat capacity (specific heat) decreases in the low temperature region, so these synergistic effects exert extremely good characteristics as an electrical insulator for heaters and as a soaking plate. .

As described above, the heating elements 54 are arranged substantially evenly over the whole so as to equalize the amount of heat generated in each part of the heater. For example, a mounting hole 58 is formed in the central portion. In this case, in order to compensate the heat radiation amount in this portion, a heating element is arranged in a ring shape at the peripheral portion of the mounting hole 58. The power supply leads 60 are connected to both ends of the heating element 54. As shown in FIG. 2, the heater 52 configured in this manner has a heater housing groove 64 formed in an upper portion of a heater fixing base 62 provided on the upper surface of the susceptor support base 10 with its upper surface at the same level and completely. Housed in. The heater fixing base 62 is made of a material having good thermal conductivity, such as aluminum. The size of the heater 52 is preferably set to be substantially the same as or larger than the area of the wafer, and the cooling heat from the cooling jacket 16 located below the heater 52 is controlled to be transferred to the wafer W. Then, the temperature of the wafer W can be adjusted.

A through hole (not shown) through which a pusher pin or the like penetrates the temperature adjusting heater 52 and the heater fixing base 62.
Etc. are formed. An appropriate number of bolt holes 64 are formed in the peripheral portion of the heater fixing base 62, and the fixing base 62 is detachably attached to the susceptor support base 10 side with bolts 66. In addition, an accommodation recess 68 for accommodating the entire heater fixing base 62 is provided on the lower surface of the susceptor 14.
The heater fixing base 62 is connected to the gas passage 30 in order to supply a heat transfer medium such as He to the boundary between the upper surface of the heater 52 and the lower surface of the accommodation recess 68 of the susceptor 14. A branched path 70 (see FIG. 1) is formed. Then, the power supply lead 60 of the heater 52
An electric power source 74 is connected to the heater 52 via a filter 72 so that a predetermined electric power can be supplied to the heater 52.

In addition, the electrostatic chuck 22 has a thermometer, for example, a fluorotropic thermometer, which utilizes the fact that the round-trip time of light changes depending on the temperature in order to detect the wafer temperature.
temperature detector 76 composed of try (trade name) and thermocouple
Is provided. And, in this temperature detector 76,
The temperature detection lead 78 for transmitting the detected value is connected. The temperature detecting lead 78 serves as a temperature detector 76 and is a fluoroscopic thermometer.
When using “mometry” (trade name), it is composed of an optical fiber, but when using a thermocouple, a normal conductor is used. In this case, a filter 80 for removing high frequency noise is inserted in the middle. It is input to a control unit 82 that is provided and controls the entire apparatus, such as a computer. The control unit 82 controls the entire apparatus by a predetermined program as described above. For example, the high frequency power source 38, the electric power source 74 to the heater 52, and the direct current high voltage source 28 to the electrostatic chuck 22 are supplied. Control distribution. Also,
An insulator 84 is provided in the penetrating portion of the pipe lead 34 at the bottom of the processing container to electrically insulate it from the container side.

Next, the operation of this embodiment configured as described above will be described. First, the wafer W is placed on the upper portion of the susceptor 14 of the processing container 4 which is depressurized to a predetermined pressure from a load lock chamber (not shown), for example, about 1 × 10 ⁻⁴ to several Torr, and the wafer W is placed by the electrostatic chuck 22. Adsorbed and held on the susceptor 14 side by Coulomb force. Then, a high frequency is applied between the upper electrode 44 and the lower electrode (susceptor) 14 via the pipe lead 34 to generate plasma, and at the same time, a process gas is caused to flow from the upper electrode 44 side into the processing space for etching. Perform processing. Also,
In order to perform the low temperature etching, a coolant, for example, liquid nitrogen is circulated in the cooling jacket 16 of the susceptor support 10 to maintain this portion at −196 ° C., and the cold heat from this portion is supplied to the wafer W via the susceptor 14 on the upper portion. Then, it is designed to be cooled.

In this case, the cooling jacket 16 and the wafer W
A temperature adjustment heater 52 is provided between the temperature adjustment unit and the temperature adjustment unit, and the temperature at which the wafer W is cooled is adjusted by adjusting the amount of heat generated in this portion, so that the wafer W has a predetermined temperature, for example, -150 ° C to -1.
Maintain around 80 ° C. In the conventional apparatus, the wafer temperature is controlled by controlling the temperature of the cooling medium itself. Further, the distance between the cooling jacket and the wafer is long and there are many interfaces, so the thermal response is very poor. . On the other hand, in this embodiment, as described above, the cooling jacket 16 is fixed at a constant low temperature, for example, −196 ° C., whereas the heater 52 is mounted on the wafer W by, for example, 15 to 15.
Since it is installed close to a distance of up to 20 mm,
This change in the amount of heat generated by the heater 52 promptly appears as a change in the temperature of the wafer W. Therefore, the thermal responsiveness is good and the wafer temperature can be quickly controlled. Therefore, the heater 5
Wafer cooling temperature only by liquid nitrogen when 2 is turned off, for example, -160 ° C (temperature difference 36 ° C between liquid nitrogen (-196 ° C) and liquid nitrogen (temperature difference generated due to thermal resistance of susceptor) is the minimum temperature) As a value, it becomes possible to control the wafer temperature quickly and linearly within the temperature range up to room temperature.

He is also provided on the interface between the heater 52 and the susceptor 14 and on the lower surface of the wafer W via the gas passage 30.
Since the heat transfer accelerating gas such as the above is introduced, the heat transfer efficiency between the upper and lower parts does not deteriorate, and the above-mentioned thermal responsiveness can be further improved. Further, when changing the wafer processing temperature from −150 ° C. to −50 ° C., for example, the control unit 8
The current flowing through the resistance heating element 54 of the heater 52 is rapidly increased by the control of No. 2 to increase the heater temperature at once, for example, 2 to 3
The cooling heat supplied to the wafer W from the cooling jacket 16 is controlled by controlling the cooling heat which is increased over a period of time to bring the wafer to a desired temperature, for example, −5.
Keep at 0 ° C. In this case, a large thermal shock is applied to the insulator 56 of the heater 52 due to the rapid temperature change. Particularly, in the present embodiment, since AlN having high thermal shock resistance is used as the insulator 56, a rapid thermal shock is caused. It is possible to suppress the occurrence of cracks and fractures even with changes.

When the wafer processing temperature is changed as described above, the temperature may be suddenly increased or decreased, and even if a large thermal stress is generated inside the material, the destruction of the insulator material is prevented. can do. Furthermore, since this AlN has a much higher thermal conductivity than that of a conventional ceramic heater, for example, the heat is well transferred in the plane direction of the heater, and therefore the in-plane uniformity of the wafer temperature can be increased. Further, since this AlN material is cheaper than the conventionally used SiC material, the material cost is not increased.

When replacing the susceptor, which is a consumable item damaged by plasma, the susceptor 14 can be easily removed by loosening the bolt 12 connecting the susceptor 14 and the susceptor support 10. Further, when the heater 52 is damaged due to overcurrent and the heater is deteriorated due to its life, maintenance work such as heater replacement is performed. In this case, the bolts are further removed with the susceptor 14 removed as described above. By removing 66, the heater 52 can be removed from the susceptor support 10 together with the heater fixing base 62, and the replacement work of the heater 52 can be easily performed.

In the above embodiment, the resistance heating element 54 of the heater 52 has a shape similar to a meandering shape, but the shape is not limited to this, and it may be formed in a spiral shape, for example. Further, in the above embodiment, the case where liquid nitrogen is used as the cooling medium has been described, but the present invention is not limited to this, and for example, liquid helium or the like may be used as the cooling medium. In the above embodiment, the case where the mounting table is used in the plasma etching apparatus has been described, but the present invention is not limited to this, and if the apparatus needs to hold the wafer to process the wafer, what kind of apparatus, Of course, it can be applied to a CVD apparatus, an ashing apparatus, a sputtering apparatus and the like.

[0025]

As described above, according to the present invention,
The following excellent operational effects can be exhibited. Since aluminum nitride, which has excellent thermal shock resistance and thermal conductivity, is used as the insulator of the temperature adjustment heater, even if a large thermal stress occurs inside the material due to a rapid temperature increase or decrease,
It is possible to significantly suppress the occurrence of cracks and breakage in this insulator, and it is possible to exhibit a high watt density. Therefore, the temperature of the wafer can be rapidly changed, and the overall processing speed can be accelerated. Further, since aluminum nitride has a good thermal conductivity, heat can be transferred quickly within the heater surface, and therefore the in-plane uniformity of the temperature of the object to be processed can be greatly improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a processing apparatus according to the present invention.

FIG. 2 is a schematic exploded view showing a mounting table of the processing apparatus shown in FIG.

FIG. 3 is a plan view showing a temperature adjusting heater used in the apparatus of the present invention.

4 is a cross-sectional view of the heater shown in FIG.

FIG. 5 is a graph showing the relationship between the thermal conductivity and the heat capacity (specific heat) with respect to the temperature of AlN.

[Explanation of symbols]

 4 processing container 8 mounting table 10 susceptor support 14 susceptor (lower electrode) 16 cooling jacket (cooling means) 22 electrostatic chuck (chuck) 26 voltage supply lead 28 direct current high voltage power supply 34 pipe lead 38 high frequency power supply 44 upper electrode 52 temperature Adjustment heater 54 Resistance heating element 56 Insulator 60 Power supply lead W Object to be processed (semiconductor wafer)

Claims (1)

[Claims] 1. A processing apparatus comprising a processing container having a chuck portion for holding and holding an object to be processed in an upper part and a mounting table having cooling means for cooling the object to be processed in a lower part, wherein the chuck is provided. Between the part and the cooling means,
A processing apparatus comprising a temperature adjusting heater using aluminum nitride as an insulator for adjusting the cold heat supplied to the object to be processed.