JP3181421B2 - Processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing apparatus such as an etching apparatus.

[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 etching or the like. This etching process is generally performed at a temperature near room temperature. However, due to the demand for miniaturization of integrated circuits and high integration, an increase in the selectivity between the substrate and the substrate during etching and Securing anisotropy is strongly desired. Under these circumstances, a so-called low-temperature etching method has recently been developed in which a wafer is cooled to an extremely low temperature of about -150 ° C. using, for example, liquid nitrogen, and etching is performed under reduced pressure in this state. Has been reached.

According to this low-temperature etching process, for example, when a polysilicon or silicon oxide film is etched, the selectivity with respect to a base can be greatly increased as compared with the conventional method. For example, when a contact hole is formed, the angle of the side wall of the hole can be formed, and a sharp hole close to 90 ° can be formed. In an apparatus for performing such an etching process, it is very difficult to secure the sealing property inside the processing chamber because the processing itself is performed at a low temperature, and therefore, it is necessary to provide a sealing property between the members constituting the processing apparatus. A sealing member such as an O-ring made of fluoro rubber or a Teflon ring with a built-in spring is interposed in the part to be sealed, and the sealing property is secured by a tightening force per unit circumference of about 3 to 5 kgf / cm in a normal temperature etching process. However, unlike the conventional etching apparatus, both members are fastened with a strong fastening force per unit circumference of, for example, 20 to 100 kgf / cm, using a large number of fastening bolts for low-temperature treatment. It has been attempted to ensure.

[0004]

The etching apparatus itself is usually made of a relatively soft metal material having good workability, such as aluminum, and therefore has a large clamping force per unit circumference as described above. When the member is tightened by the method described above, the material itself is plastically deformed, and as a result, there is an improvement in that the sealing property is deteriorated. In addition, the seal member made of fluoro rubber or Teflon deteriorates due to extremely low temperature,
As a result, there is an improvement in that the sealing property is also reduced. Furthermore, because many tightening bolts are used,
There is also an improvement that it takes a lot of time to replace parts during maintenance or trouble. The present invention has been devised in view of the above problems and effectively solving them. An object of the present invention is to provide a processing apparatus capable of improving the sealing performance by using a sealing member suitable for an ultra-low temperature.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a susceptor on which an object to be processed is placed and a susceptor for supporting the susceptor in a processing chamber capable of being evacuated. Through a gas passage that passes through the support base,
By supplying a heat transfer gas to the back surface of the object to be processed, in a processing apparatus for processing the object to be processed under reduced pressure and at a low temperature, a joining portion between the susceptor and the susceptor support base may be made of a highly elastic material. A ring-shaped seal member formed by applying a coating film having high ductility to the surface of the seal base material is formed so as to be interposed in a ring shape around the gas passage, and the ring-shaped seal member is
A first ring-shaped sealing member and a second ring-shaped sealing member having different diameters from each other;
The first and second ring-shaped seal members.
The ring-shaped sealing member is double-laid on the same surface of the joint.
And are arranged concentrically .

[0006]

According to the present invention, as described above, a sealing member in which a coating film having high ductility is applied to the surface of a sealing base material made of a highly elastic material is provided at a joint between members constituting a processing apparatus. Interposed therebetween, the conformability between the member surface and the coating film of the seal member in contact with the member surface is improved while maintaining the desired elasticity even at an extremely low temperature, and it is possible to ensure high sealability.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the processing apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional configuration view showing one embodiment of a processing apparatus according to the present invention, FIG. 2 is an enlarged cross-sectional view showing the vicinity of a seal portion in FIG. 1, and FIG. 3 is a perspective view showing a seal member used in the apparatus in FIG. FIG. In this embodiment, a low-temperature plasma etching apparatus will be described as an example of a processing apparatus.

As shown in the figure, this etching apparatus 2
The processing container 4 has a cylindrical or rectangular shape formed of a conductive material, for example, aluminum or the like.
A substantially columnar mounting table 8 for mounting an object to be processed, for example, a semiconductor wafer W, is accommodated at the bottom of the substrate via an insulating plate 6 made of ceramic or the like. The mounting table 8 is configured by assembling a plurality of members, which will be described later, formed of aluminum or the like with bolts or the like. More specifically, the mounting table 8 includes a susceptor support table 10 formed of aluminum or the like in a cylindrical shape, and a bolt 12
And a susceptor 14 made of aluminum or the like provided detachably.

The susceptor support 10 has cooling means,
For example, a cooling jacket 16 is provided, and a cooling medium such as liquid nitrogen is
8, circulates through the jacket, and the gas due to the evaporation of the liquid nitrogen is discharged from the refrigerant discharge pipe 20 to the outside of the container. Therefore, the cold heat of the liquid nitrogen at −196 ° C. is supplied from the cooling jacket 16 through the susceptor 14 to the wafer W.
And cooled to a desired temperature.

The susceptor 14 is formed in a disk shape having a central upper end in a protruding shape, and an electrostatic chuck 22 is formed in the center of the wafer mounting portion with an area substantially equal to the wafer area. The electrostatic chuck 22 is formed, for example, by sandwiching a conductive film 24 such as a copper foil between two polymer polyimide films in an insulated state. The conductive film 24 is cut by a voltage supply lead 26 in the middle of a high frequency. The filter 28 is connected to a variable DC high voltage source 30 via a coil, for example. Therefore, by applying a high voltage to the conductive film 24, the wafer W can be suction-held on the upper surface of the chuck 22 by Coulomb force.

The susceptor support 10 and the susceptor 14 are supplied with a heat transfer gas such as He through the susceptor support 10 and the susceptor 14 to the back surface of the wafer W, their joints, joints between the members constituting the susceptor 14, and the like. Gas passage 32 is formed. The electrostatic chuck 22 is also provided with a number of ventilation holes (not shown) through which the heat transfer gas passes.
Further, an annular focus ring 34 is arranged on the upper end peripheral portion of the susceptor 14 so as to surround the wafer W.
The focus ring 34 is made of an insulating material that does not attract reactive ions, and allows the reactive ions to effectively enter only the inner semiconductor wafer W.

A pipe lead 36 made of a hollow conductor is connected to the susceptor 14 through the susceptor support 10.
6 has a matching capacitor 40 via a wiring 38.
A high-frequency power supply 42 for generating a plasma of, for example, 13.56 MHz or 40.68 MHz is sequentially connected. Therefore, the susceptor 14 is configured as a lower electrode. A grounded upper electrode 44 is disposed above the susceptor 14 at a distance of about 15 to 20 mm therefrom. The upper electrode 44 is connected to a process gas, for example, CF through a gas supply pipe 46. An etching gas such as ₄ is supplied, and the etching gas is blown out from a large number of small holes 48 formed on the electrode surface of the upper electrode 44 into a processing space below.

An exhaust pipe 50 is connected to the lower side wall of the processing container 4 so that the atmosphere in the processing container 4 can be exhausted by an exhaust pump (not shown), and the central side wall is not shown. A gate valve is provided, through which a wafer is loaded and unloaded.

A temperature adjusting heater 52 is provided below the susceptor between the electrostatic chuck 22 and the cooling jacket 16. The heater 52 is made of a plate-shaped ceramic heater having a thickness of about several mm.
Are completely accommodated in an upper portion of a heater fixing base 54 fixed to the upper surface of the susceptor support base 10 by bolts or the like (not shown) with the upper surface at the same level. Heater fixing base 54
Is made of a material having good thermal conductivity, for example, aluminum. The size of the heater 52 is preferably set so as to be substantially the same as or larger than the wafer area, and it is assumed that the cooling heat from the cooling jacket 16 located below this is conducted to the wafer W. The temperature of the wafer W can be controlled and adjusted. The temperature adjusting heater 52 and the heater fixing base 54 are formed with through holes (not shown) through which pusher pins and the like pass. An accommodation recess 56 for accommodating the entire heater fixing base 54 is formed on the lower surface of the susceptor 14. A branch path 58 connected to the gas passage 32 is formed to supply a heat transfer medium such as He to the boundary of the gas passage 32. A power supply lead 60 is connected to the heater 52, and
0 is connected to a power source 62 to supply predetermined power to the heater 5.
2 can be supplied.

The electrostatic chuck 22 has a thermometer for detecting a wafer temperature, for example, a fluorooptic thermometer.
A temperature detector 64 including a meter, a thermocouple, and the like is provided. The temperature detector 64 is connected to a temperature detection lead 66 for transmitting a detected value. The temperature detection lead 66 is formed of an optical fiber when a fluorooptic thermometer is used, but a normal conductor is used when a thermocouple is used.
8 is connected.

Also, various wirings which are easily affected by high frequency for plasma generation, such as a power supply lead 60 connected to a heater, a voltage supply lead 26 connected to the electrostatic chuck 22, and a temperature detector 64 are connected. Temperature detection lead 6
All 6 are accommodated in a pipe lead 36 for supplying a high frequency for plasma, so that high frequency noise does not affect the outside. An insulator 70 is interposed at the penetrating portion of the pipe lead 36 at the bottom of the processing container to achieve electrical insulation from the container side. Further, a grounded shield 72 is provided on the outer periphery of the pipe lead 36 extending outside the container, and is configured so that high frequency does not leak to the outside.

A seal member 74, which is a feature of the present invention, is interposed at a joint between the members constituting the apparatus and requiring a hermetic seal. The airtightness is maintained. This sealing member 7
Numeral 4 is interposed in a portion through which a gas passage 32 for supplying helium and a pipe lead 36 communicating with the atmosphere penetrate, and a portion where leakage of supplied helium into a container is to be prevented. Therefore, in the illustrated example, the susceptor support 1
First, a pair of seal members 74A, 74A, 7
4B is interposed in a ring shape, and the accommodation recess 5 of the susceptor 14 is provided.
The other seal member 74C is interposed at a joint 78 between the lower surface of the heater 6 and the upper surface of the heater fixing base 54, and the susceptor 14
Another pair of seal members 74D and 74E are interposed in a ring shape at a joint portion 80 between the upper surface of the electrostatic chuck 22 and the lower surface of the electrostatic chuck 22. Of the pair of seal members interposed between the susceptor support 10 and the susceptor 14, the seal member 7 having a small diameter is used.
4B is arranged so as to surround the gas passage 32 and the gas leak from the pipe lead 36 side so as to shut off the leakage gas. The other large-diameter seal member 74A is
The susceptor support and the susceptor are arranged on the peripheral edge to form a double seal structure.

A seal member 74C interposed between the heater fixing base 54 and the lower surface of the housing recess 56 is disposed on the outer peripheral side of the heater 52 for temperature adjustment, and the upper and lower portions to be supplied to the inside thereof are provided. The helium gas for heat transfer in the direction is prevented from leaking into the processing container 4. Among the pair of seal members interposed between the susceptor 14 and the electrostatic chuck 22, the seal member 74E having a small diameter is disposed on the outer peripheral side of the upper end discharge port of the branched gas passage 32, and is provided inside the seal member 74E. The helium gas for heat transfer to be supplied is prevented from leaking into the processing container 4 as described above. A seal member 74D having a large diameter is arranged on the outer peripheral side of the seal member 74E having a small diameter to form a double seal structure.

FIG. 2 is an enlarged view showing a state in which each seal member 74 is interposed. In the illustrated example, as an example, upper and lower members, for example, the upper surface of the heater fixing base 54 and the lower surface of the accommodation recess 56 are formed. A small gap S having a width of about 0.1 mm is formed between these members in order to appropriately retain the heat transfer gas. This seal member 74D is accommodated in a lower member, that is, a ring-shaped seal groove 82 having a rectangular cross section formed on the upper surface of the heater fixing base 54 in the illustrated example, similarly to the other seal members. The dimension of the groove or the dimension of the sealing member is set so that the upper and lower ends thereof are in contact with both members.

Each seal member 74 is configured as shown in FIG. That is, the sealing base material 84 has a cross section that is bendable like the letter C of the alphabet and is formed in a ring shape, and a coating film 86 is formed on the surface thereof. As the seal base material 84, since the processing gas is a corrosive gas, a highly elastic material having corrosion resistance, for example, a high-grade stainless steel of SUS300 such as SUS316 or a nickel-cobalt alloy, for example, Inconel (trade name) , Hastelloy (trade name) and the like are used.
Other than these materials, any material may be used as long as it has a high elastic modulus and a high yield point in order to guarantee a high elastic modulus even at a low temperature.

As the coating film 86, a material having high ductility or malleability, for example, indium (I
n), gold (Au), silver (Ag), zinc (Zn), copper (C
Metal materials such as u) and polymer materials such as Teflon and high-molecular polyethylene are used. By forming this type of coating film 86, the conformability with the member surface is improved.
Even at a very low temperature of about 150 ° C., the sealing property does not deteriorate. The coating film 86 only needs to be applied to at least a portion that comes into contact with the surface of the member at the time of interposition. In the illustrated example, the coating film 86 is applied only to the outer surface of the seal base material 84 and is not applied to the inner surface.

The sealing member 74 has a tightening force per unit circumferential length, for example, 10 kg, with an appropriate number of bolts.
At this time, the average surface roughness Ra of the seal groove 82 is set to 0.2 μm (0.8 S) or less, and the hardness of the aluminum member is set to Hv 70 or less. Note that, in the illustrated example, the case where the seal member is provided only at a typical joint portion for ease of explanation has been described. In this type of etching apparatus, for example, about 20 sealing members are provided.

Next, the operation of the embodiment constructed as described above will be described. First, the wafer W is placed on the susceptor 14 in the processing chamber ⁴ which has been reduced in pressure from a load lock chamber (not shown) to a predetermined pressure, for example, about 1 × 10 ⁻⁴ to several Torr. Thus, the susceptor 14 is sucked and held by the Coulomb force. Then, a high frequency is applied between the upper electrode 44 and the lower electrode (susceptor) 14 through a pipe lead 36 to generate plasma, and at the same time, a process gas flows from the upper electrode 44 side into the processing space, thereby performing an etching process. I do.

Also, since the wafer is excessively heated by the heat of the plasma above a predetermined set temperature, a coolant, for example, liquid nitrogen is passed through the cooling jacket 16 of the susceptor support 10 to cool the wafer. To -196 ° C
Is supplied to the wafer W through the upper susceptor 14, and is cooled to maintain a desired low temperature state. Thereby, the wafer W
Is subjected to low-temperature etching. The temperature at which the wafer W is cooled is adjusted by adjusting the amount of heat generated by the temperature adjusting heater 52 provided between the cooling jacket 16 and the wafer W, and the wafer W is cooled to a predetermined temperature, for example, −15.
Maintain at about 0 ° C to 10 ° C. The temperature of the wafer can be raised to room temperature or higher, for example, to 60 ° C. by controlling the amount of heat generated by the heater and the flow rate of the refrigerant in the jacket 16.

Further, in order to efficiently transmit the cold heat in the cooling jacket 16 to the wafer W side, the susceptor support 10 and the joining portion of the susceptor 14 or the joining portion between the members constituting the susceptor 14 are used for heat transfer as necessary. Supply of helium gas, and pipe leads 3
6 so that the joint 7
6, 78, 80, a small gap, for example gap S
Helium gas and atmospheric components tend to leak out into the processing container 4 under reduced pressure via the like. However, in this embodiment, since each of the joints 76, 78, and 80 has the sealing member 74 as shown in FIG. It is possible to prevent leakage into the container via the. For example, when liquid nitrogen is used as a coolant, the temperature of these joints is cooled to a maximum of -196 ° C., so that the conventional Teflon or fluoro rubber sealing member loses elasticity and deteriorates in sealing performance. However, in the present embodiment, the seal base material 84 is formed of a material having a high elastic modulus even at an extremely low temperature, and the surface thereof is ductile or malleable in order to maintain high conformability with a member in contact with the seal base material. A coating film 86 made of a material having a large size is applied. Therefore, even when these seal members 74 are exposed to an extremely low temperature, the elasticity of the seal members 74 having a C-shaped cross section is maintained high by bending vertically in the illustrated example, and the members (FIG. 2) In the heater fixing table 54
At the contact points P1 and P2 between the contact recesses 56), the coating film 86 is interposed, so that the conformability with the member surface is maintained high, and as a result, the sealing performance at this portion is maintained high. It becomes possible.

In this embodiment, the number of bolts for tightening the members is reduced so that the tightening force per unit circumferential length of the seal member 74 is 10 kgf, which is much smaller than that of the conventional low-temperature etching apparatus. / Cm and the average surface roughness Ra of the seal groove is 0.2 μm
And the Vickers hardness Hv of the aluminum member was set to about 70 (the sealing pressure was 1 kg).
f / cm ² ), and the helium gas leak rate is 10
^-6 Torr · liter / sec or less, it was found that high sealing performance could be secured. As described above, sufficient sealing performance can be ensured even at an extremely low temperature with a tightening force per unit circumference much smaller than the tightening force per unit circumference for the seal member of the conventional low-temperature etching apparatus. The number of bolts used for tightening the members can be reduced, and maintenance can be improved.

In the seal member 74 shown in FIGS. 2 and 3, the cross-sectional shape of the seal base material 84 is shaped like the letter C of the alphabet, but is not limited to this. For example, as shown in FIG. The cross-sectional shape of the seal base material 84 may be formed into a so-called cocoon shape with one end notched. According to this, the upper and lower portions come into contact with the surface of the member at two points, respectively, so that the sealing performance can be further improved. The refrigerant to be used is not limited to liquid nitrogen, and other refrigerants such as liquid helium, liquid hydrogen, liquid oxygen and the like can be used.
In the above embodiment, the case where the present invention is applied to a low-temperature plasma etching apparatus has been described.However, the present invention is not limited to this.
For example, the present invention can be applied to a prober device for inspecting electrical characteristics of a wafer or an LCD at a low temperature, an electron microscope for observing a sample under a low-temperature vacuum, and the like.

[0028]

As described above, according to the processing apparatus of the present invention, the following excellent operational effects can be exhibited. Since a sealing member that does not lose elasticity even at low temperatures is used, cool heat is applied from the susceptor support to the susceptor.
It is possible to perform a desired process on the object to be processed while transmitting efficiently and without lowering the sealing property. Further, the tightening force per unit circumferential length can be reduced as compared with the conventional low-temperature processing apparatus, so that the number of bolts required for tightening can be reduced, and the maintenance performance can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram illustrating an embodiment of a processing apparatus according to the present invention.

FIG. 2 is an enlarged sectional view showing the vicinity of a seal portion in FIG.

FIG. 3 is a perspective view showing a seal member used in the apparatus of FIG.

FIG. 4 is an enlarged sectional view showing another seal member used in the present invention.

[Explanation of symbols]

 2 Etching apparatus 4 Processing container 10 Susceptor support 14 Susceptor 16 Cooling jacket 22 Electrostatic chuck 42 High frequency power supply 44 Upper electrode 74 Sealing member 76, 78, 80 Joint 82 Seal groove 84 Seal base material 86 Coating film S gap W Semiconductor wafer (Object to be processed)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/3065 B01J 3/02 H01L 21/68

Claims (5)

(57) [Claims] In a processing vessel which can be evacuated, via a gas passage penetrating a susceptor on which an object to be processed is mounted and a susceptor support for supporting the susceptor,
In a processing apparatus for processing the object to be processed under reduced pressure and in a low temperature state by supplying a heat transfer gas to the back surface of the object to be processed, a joining portion between the susceptor and the susceptor support may be made of a highly elastic material. When a ring-shaped sealing member formed by applying a coating film having high ductility to the surface of the sealing base material is configured to be interposed in a ring shape around the gas passage.
In both cases, the ring-shaped seal members have different diameters from each other.
A first ring-shaped seal member and a second ring-shaped seal
And the first and second ring-shaped seals.
The conical member is doubled on the same surface of the joint
A processing device characterized by being arranged . 2. A gas penetrating a susceptor provided on an upper surface thereof with an electrostatic chuck for adsorbing an object to be mounted and a susceptor support for supporting the susceptor in a vacuum-evacuable processing container. In a processing apparatus for processing the object under reduced pressure and at a low temperature by supplying a heat transfer gas to a back surface of the object through a passage, a bonding portion between the susceptor and the electrostatic chuck is provided. , as well as configured to be interposed in a ring around the upper end discharge port of the gas passage an annular sealing member formed by a coating film having a high ductility to the surface of the sealing base material made of a highly elastic material, the The ring-shaped sealing members are
A first ring-shaped sealing member having a different diameter and a second ring-shaped sealing member;
The first and second rings.
The sealing member is shaped like a double on the same surface of the joint.
A processing device characterized by being arranged concentrically . The method according to claim 3 wherein said susceptor support, the processing device according to claim 1 or 2, characterized in that the cooling jacket for cooling the object to be processed is provided. 4. The processing apparatus according to claim 3, wherein liquid nitrogen flows through the cooling jacket. Wherein said sealing member, in order to increase the flexibility, processing apparatus according to any one of claims 1 to 4, characterized in that a part of the cross section is cut out.