JPH08139039A - High frequency shield heater - Google Patents

Abstract

PURPOSE: To prevent a high frequency current from flowing in a heater and AC supply wiring for the heater, by constituting a heater in a heater unit, as a sheathed heater composed of a high resistivity metal conductor, insulator, and a metal outer skin covering the whole outer periphery of the insulator, and by grounding the metal outer skin. CONSTITUTION: As a heater, a sheathed heater 220 is used, which is a heating element formed by covering a high resistance wire 221 with insulator 223 and metal sheath or outer skin 225. The sheathed h,eater 220 is held by a retaining pedestal 27. Between the pedestal 27 and a heater base 101, a bellows 26 is used to maintain the airtight of a reaction furnace. Only the nichrom wire 221 of the sheathed heater 220 is connected with an AC power supply 219. A return line 230 composed of metal conductor is connected with the part between the retaining pedestal 27 made of metal and a metal chamber base 101. Thereby a high frequency current which has passed the heater unit 21 travels the metal outer skin 225 of the sheathed heater, and is returned by the return line 230, so that the heater itself inside the sheathed heater is shielded from high frequency.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a lower electrode. More specifically, the present invention relates to a heater used in a lower electrode for a gas phase reaction apparatus that performs a film formation process using plasma.

[0002]

2. Description of the Related Art In manufacturing a semiconductor IC, there is a step of forming a thin film of silicon oxide on the surface of a substrate. Chemical vapor deposition (CVD) is used as a method of forming a thin film. There are three CVD methods, an atmospheric method, a decompression method and a plasma method, but the plasma method is attracting attention as a suitable method for a recent ultra LSI that requires a high quality and highly accurate thin film. .

In the plasma method, a high-frequency voltage is applied to a reaction gas injected in a vacuum to form a plasma, and energy required for the reaction is obtained. Therefore, a uniform film thickness and a good film quality can be obtained. Moreover, it is excellent in many respects such as a high film formation speed.

For example, SiH ₄ or the like has been used as a material for forming a silicon oxide film by the plasma method. However, a decrease in step coverage (step coverage) has become a problem with the miniaturization of semiconductor devices. Liquid tetraethylorthosilicate (TEOS) [Si (OC ₂ H ₅ ) ₄ ] has recently been used in place of this monosilane gas. This is because TEOS can form a dense film having excellent step coverage. When a silicon oxide film is formed using TEOS, TEOS is heated and vaporized to form TEOS gas, which is mixed with oxygen gas and supplied to the reaction furnace.

FIG. 2 is a schematic configuration diagram of an example of a conventional plasma CVD apparatus 1. In the figure, a reaction furnace (chamber) 10 is made airtight, a metal nozzle portion 30 is fixed to a lid plate 102 of the reaction furnace 10, and an aluminum lower portion is provided therewith, and a large number of minute holes 41 penetrating from the upper surface to the lower surface are provided. The disk-shaped shower electrode 40 is supported by the insulating ring 103. This is the upper electrode 32. A high frequency power supply 7 that applies a high frequency voltage to the shower electrode 40 is provided.

A lower electrode 20 is provided so as to face the upper electrode 32. The lower electrode 20 is supported by a pillar 25, and the pillar 25 is configured to be movable up and down so that the distance between the electrodes can be changed. Reference numeral 26 indicates an airtight bellows. Further, reference numeral 27 indicates a metal support base. A susceptor 22 is disposed above the pillar 25, a heater unit 21 is disposed below the susceptor 22, and a heater cover 23 is provided around the susceptor 22 and the heater unit 21. The susceptor 22 is supported by the support column 25 via, for example, a metal engaging member 28 and an insulating member 29. Further, the susceptor is a conductor 31 connected to the metal engaging member 28 and the reactor base 1.
It is grounded through 01.

The heater unit 21 has heaters 211 made of nichrome wire or the like arranged on a heater base 213.
It has a structure in which it is sandwiched between the heater retainer 215 and the heater retainer 215. The heater 211 is connected to an AC current supply wiring 217 formed by coating a metal conductor such as a nichrome wire with an insulator. The wiring 217 is held by the bellows 26 and the support pedestal 27, as in the case of the support column 25.
The wiring 217 is connected to the AC power source 219 outside the furnace.

In the reaction process, the side surface 1 of the reaction furnace 10 is used.
05, the gate 51 of the loading / unloading path 50 is opened, the substrate 6 is loaded by the carriage 52, and the susceptor 2 is loaded.
It is placed on the upper surface of the No. 2 approximately at the center. After the gate is closed and the inside of the reactor is evacuated to a predetermined degree of vacuum by exhausting air from the duct 104, when the heater 21 heats the susceptor 22 and the substrate placed on the susceptor 22 reaches a predetermined temperature, the inlet 34 is discharged from the inlet 34. A predetermined reaction gas (for example, TEOS and oxygen gas) is fed into the reaction furnace. Gas is nozzle 30
After that, the particles are ejected toward the substrate from the minute holes 41 of the shower electrode 40.

However, in the lower electrode 20 of the conventional plasma CVD apparatus as shown in FIG. 2, the susceptor (conductor) is used.
22, heater retainer (insulator) 215 and heater (conductor)
The heater 211 and the wiring 217 for supplying an AC current to the heater 211 form a structural capacitor together with the element 211 and serve as a kind of antenna. Therefore, when plasma is ignited, a high frequency may flow through the heater and the wiring, and the control system (especially thyristor) of the AC power source may be damaged. Due to this damage, the control system malfunctions, the susceptor melts, and the heater turns off abnormally.
(That is, the heater suddenly turns off even if there is no command), and product defects occur due to abnormalities such as aluminum vapor deposition due to abnormal temperature rise of the heater, which is a major factor of throughput reduction.

[0010]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a high-frequency shield heater having a structure in which a high frequency hardly flows in the heater and the heater AC current supply wiring.

[0011]

[Means for Solving the Problems] The above object is to provide an upper electrode connected to a high frequency power source in the reaction furnace in a gas phase reaction apparatus having a reaction furnace and performing film formation processing by plasma in the reaction furnace. And a lower electrode facing the upper electrode, the lower electrode having at least a susceptor and a heater unit disposed on the lower surface side of the susceptor, and the heater in the heater unit is a reactor. In a lower electrode consisting of a device connected to an external AC power source, the heater in the heater unit covers a high resistance metal conductor, an insulator covering the conductor, and the entire outer peripheral surface of the insulator. This is a sheathed heater made of a metal skin, and the metal skin is grounded, and is solved by a high-frequency shield heater.

[0012]

As described above, the high-frequency shield heater of the present invention has a structure in which the metal skin of the heater outer wall is grounded. For example, when the metal skin is grounded to the chamber, the high frequency wave that has passed through the heater is conducted through the metal skin of the heater and returned to the matching box through the outer wall of the chamber, and the metal conductor itself of the heater is shielded from the high frequency wave. With this structure, it is possible to effectively prevent the control system of the AC power source outside the reactor from being damaged by high frequency, and it is possible to prevent product defects due to malfunction.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings.

FIG. 1 is a partial schematic sectional view of a heater for a lower electrode according to the present invention. In the present invention, the conventional heater 211
The sheathed heater 220 is used for. Sheathed heater 220
Is a heating element having a high resistance wire (for example, a nichrome wire) 221 in the center, the high resistance wire 221 being buried in an insulator (for example, magnesia) 223, and wrapped with a metal sheath or an outer skin 225. This heating element can be used for both contact heating and radiant heating, and can be used up to a surface temperature of about 800 ° C. The heater unit 21 itself includes the sheathed heater 220 and the heater base 213 as in the case of the conventional apparatus shown in FIG.
Are arranged at appropriate positions and are sandwiched by the heater retainer 215. The introduction terminal portion of the sheathed heater 220 extending from the lower side of the heater unit 21 is held by a support base 27 that can move up and down, as in the configuration shown in FIG. The support pedestal 27 and the heater base 101 are connected by a bellows 26, thereby maintaining an airtight state of the reaction furnace. AC only the nichrome wire 221 of the sheathed heater 220 protruding from the support base 27 to the outside.
Connect to power supply 219. The nichrome wire between the protruding portion and the AC power source can be coated with an insulating coating such as polyvinyl chloride.

The sheath 225 of the sheathed heater 220 is made of a metal such as stainless steel or a metal coated with nickel or nickel or aluminum. Therefore, when the sheath 225 is held by the support pedestal 27 also made of metal, high frequency waves passing through the metal sheath 225 are supported. It is also transmitted to the pedestal 27. Therefore, in the present invention, the return line 23 made of a metal conductor is provided between the metal support pedestal 27 and the metal chamber base 101.
0 is connected. As a result, the heater unit 21
The high frequency wave that has passed through passes through the metal sheath 225 of the sheathed heater and is returned to the matching box through the chamber base 101 by the support pedestal 27 and the return line 230, and the heater itself inside the sheathed heater is shielded from the high frequency wave. With this structure, the control system of the AC power supply is protected from high frequencies, and product defects due to malfunction can be prevented.

The lower electrode using the sheathed heater having the ground structure of the present invention can be used not only in the plasma CVD apparatus but also in a gas phase reaction apparatus using plasma, for example, lower electrodes such as an etcher and an asher.

[0017]

As described above, according to the present invention,
The sheath of the sheathed heater used in the heater unit is grounded to the chamber. Therefore, the high frequency wave that has passed through the heater unit is conducted through the metal skin of the sheathed heater and returned to the matching box through the chamber base by the support pedestal and the return line, and the heater itself inside the sheathed heater is shielded from the high frequency wave.
With this structure, the control system of the AC power supply is protected from high frequencies, and product defects due to malfunction of the heater can be prevented.

[Brief description of drawings]

FIG. 1 is a partial schematic cross-sectional view of an example of a lower electrode using a high-frequency shield heater having a sheathed heater ground structure of the present invention.

FIG. 2 is a schematic cross-sectional view of an example of a plasma CVD apparatus having a lower electrode including a conventional lower electrode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plasma CVD apparatus 6 Substrate 7 High frequency power supply 10 Reactor 20 Lower electrode 21 Heater unit 22 Susceptor 23 Heater cover 25 Strut 26 Bellows 29 Insulation material 31 Ground wire 32 Upper electrode 101 Chamber base 211 Heater 213 Heater base 215 Heater foot 217 AC current Supply wiring 219 AC power supply 220 Sheath heater 221 Nichrome wire 223 Magnesia insulation coating 225 Stainless metal skin 230 Return line

Claims (3)

[Claims] 1. A gas-phase reaction apparatus having a reaction furnace for performing a film formation process by plasma in the reaction furnace, and an upper electrode connected to a high frequency power source in the reaction furnace and facing the upper electrode. A lower electrode is disposed, and the lower electrode has at least a susceptor and a heater unit disposed on the lower surface side of the susceptor, and the heater in the heater unit is connected to an AC power source outside the reaction furnace. In the lower electrode, the heater in the heater unit is a sheathed heater including a high-resistance metal conductor, an insulator covering the conductor, and a metal skin covering the entire outer peripheral surface of the insulator. A high-frequency shield heater, wherein the metal outer skin is grounded. 2. The high resistance metal conductor of the heater is a nichrome wire, the insulator covering the nichrome wire is made of magnesia, and the metal outer covering the magnesia insulator is made of stainless steel, nickel, nickel or aluminum. The high-frequency shield heater according to claim 1, which is made of a coated metal. 3. The high-frequency shield heater according to claim 1, wherein the metal outer cover of the heater is grounded by being connected to the chamber base by a return line made of a metal conductor outside the reaction furnace.