JPH09148049A - Heating heater for plasma cvd device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration or disconnection of a heating wire, due to halide produced in cleaning a reaction furnace inside, by using specific alloy as the heating wire of this heating heater, in a given plasma CVD device. SOLUTION: In this plasma CVD device, a reaction gas is jetted from a shower electrode to the surface of a wafer to be treated, heated to given temperature, by a heating heater, and the reaction gas, jetted to the shower electrode with high-frequency voltage pressurized, is made plasma to form a thin coat on the surface of the wafer. In this device, as the heating wire of a heating heater, alloy, preferably Fe or Al, is used which is added with metallic material, which is having the main component of Ni and Co, and in which halide, produced by F gas in cleaning the inside of the CVD device by F gas, has a melting point of 200 deg.C or higher.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to plasma CVD.
The present invention relates to a heater used in an apparatus, and particularly to the material of its heating wire.

[0002]

2. Description of the Related Art In the manufacture of semiconductor ICs, there is a step of forming a thin film of silicon oxide on the surface of a silicon wafer, and chemical vapor deposition (CVD) is used for forming the thin film. There are various types of CVD methods, but for recent VLSIs that require high-quality thin films, plasma CVD is used.
The method is said to be advantageous, and plasma CVD equipment is being used progressively, among which is the parallel plate type.

FIG. 3 is a block diagram of a parallel plate type plasma CVD apparatus. The plasma CVD apparatus 1 has a base plate B
An airtight reaction furnace 11 fixed to the inside, a susceptor portion 12 horizontally provided inside thereof, and a shower electrode provided parallel to the upper portion thereof.
13, a nozzle portion 14 for this, and a high frequency power source portion 15 provided outside the furnace. The susceptor unit 12 is composed of an insulating support 121 fixed to the base plate B, a heater 122 and a soaking plate 123 which are sequentially stacked on the insulating support 121, and the wafer 2 to be processed 2
Is inserted into the inside of the side wall 111 of the reaction furnace 11 and placed on the soaking plate 123, and after closing the door 112, the heater 122
And is maintained at a predetermined temperature. Nozzle part 14
For example, tetraethyl orthosilicate (TEOS) and oxygen O ₂ + helium He are supplied to the two inlets 141, 142 of the respective inlets 141, 142, and the mixed gas thereof is injected through a large number of injection holes 131 provided in the shower electrode 13. It High-frequency power supply 15 has two oscillators 151 and 152 for oscillating a frequency f ₁ and f _2, respectively, frequencies f ₁ and f ₂
Are, for example, 13.56 MHz and 400 kHz, and these are supplied to the shower electrode 13 and the soaking plate 123, respectively.
The injected mixed gas is plasmatized by the electric field generated between the two to generate silicon oxide, which is deposited on the surface of the wafer 2 to form a thin film thereof. The reacted gas is supplied to a plurality of outlets 113 on the side surface of the reactor 11.
Is discharged outside the furnace. As shown in the detailed diagram, the heater 122 has a nichrome wire 1222 sandwiched between two ceramic plates 1221a and 1221b. The AC voltage applied to both terminals is controlled by a control circuit (not shown). , The wafer 2 is maintained at a predetermined temperature.

Now, the silicon oxide generated by the above-mentioned plasma generation is the shower electrode other than the surface of the wafer 2.
13 is deposited on the inner wall of the reactor 13, the susceptor portion 12 and the reaction furnace 11 to form flakes. When the flakes are separated to a certain extent or more, they are separated and float, which adversely affects the formation of plasma, or becomes foreign matter, which contaminates the wafer 2 and deteriorates its quality. ing. FIG. 4 illustrates a cleaning method, in which the wafer 2 is not placed on the soaking plate 123, the door 112 is closed, and the heating of the heater 122 is stopped, and carbon tetrafluoride is supplied to the inlets 141 and 142. CF ₄ and oxygen O ₂ are supplied respectively, and the mixed gas of these is supplied to the shower electrode 13
And then ejected from the outlet 113. Here, when a high frequency voltage of frequency f ₁ is applied to the shower electrode 13, the mixed gas is turned into plasma, and the flakes adhering to each part are fluorinated and forcedly separated by the fluorine radicals generated thereby. Outlet with exhaust gas
It is discharged from the furnace from 113.

The above cleaning method has a problem that the nichrome wire 1222 of the heater 122 deteriorates. That is, the nichrome wire 1222 is usually one in which nickel Ni and chromium Cr are the main components and iron Fe is added thereto, while the cleaning gas is heated by the heater 122.
Since it penetrates into the gap between the two ceramic plates 1221a and 1221b from the end of the and touches the nichrome wire 1222, the CF ₄
As a result, the Cr of the nichrome wire 1222 is transformed into chromium fluoride CrF. Since CrF has a melting point at room temperature, it is easily desorbed, the specific resistance of the portion is lowered, the current density is increased and the deterioration is accelerated, and finally the heater is melted or broken by electromigration. Although nickel fluoride NiF and iron fluoride FeF are also generated by cleaning,
These melting points are much higher than room temperature, so Nichrome wire 1222
Does not contribute to the deterioration of When the nichrome wire 1222 is deteriorated and disconnected as described above, the CVD apparatus 1 is naturally unusable. Therefore, the operating state of the heater 122 is checked in a timely manner.
The heater 122 is replaced with a good product each time deterioration or disconnection is detected.

[0006]

In the above, the replacement of the heating heater 122 has a drawback that the CVD device 1 is stopped, so that the operation rate thereof is lowered. Further, the replacement heating heater 122 is necessary, and the labor and time required for the replacement are increased. The cost is not small. Originally, the deterioration of the heater 122 was caused by Cr being chromium fluoride Cr.
Since it is generated because it is transformed into F, if a heating wire containing no Cr is used, it is directly effective in preventing deterioration. This invention was made based on the above concept,
It is an object of the present invention to provide a heater using a heating wire that does not contain Cr.

[0007]

The points of the present invention are as follows:
The heating wire of the heater is one that does not contain chromium Cr, but no suitable heating wire is found for ordinary heating wires. On the other hand, the inventor of the present invention prototyped an alloy in which Cr of Nichrome wire was replaced with cobalt Co, that is, an alloy mainly composed of nickel Ni and cobalt Co, and iron Fe or aluminum Al was added thereto, As a result of testing the characteristics, by appropriately setting these composition ratios, it is possible to obtain those having specific resistance characteristics and workability almost equal to those of the nichrome wire, and this alloy also occurs in cleaning with fluorine F-based gas. It has been confirmed that the melting point of fluoride is 200 ° C. or higher and that it does not melt at room temperature, and it can be used for a heater.

The present invention is a heating heater based on the above-mentioned test results, wherein nickel (Ni) and cobalt (Co) are the main components of the heating wire of the heating heater, and the inside of the CVD apparatus is cleaned with a fluorine F-based gas. An alloy added with a metal material in which a halide generated by a fluorine F-based gas has a melting point of 200 ° C. or higher is used. The metallic material to be added is iron Fe or aluminum Al, and the composition ratio of the above alloy is Ni (50 to 80%), C.
Within the range of o (5 to 20%), Fe or Al (5 to 10%), the specific resistance of the alloy is set to an appropriate value for the heater.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The alloy used as the heating wire of the heater of the present invention has a composition ratio of Ni (50 to 80%),
By setting the content within the range of Co (5 to 20%), Fe or Al (5 to 10%), it is possible to obtain a material having a specific resistance value and workability suitable for a heater, similar to a nichrome wire,
Further, this alloy produces CoF, FeF or AlF as a fluoride during cleaning with a fluorine F-based gas, but since all of these have melting points of 200 ° C. or higher, they do not melt at room temperature, and therefore deterioration or disconnection due to cleaning occurs. Will be eliminated. As a result, a reduction in the operating rate of the CVD apparatus can be avoided, and a heating heater for replacement is not required, and the labor and cost for replacement can be saved.

[0010]

1 shows an embodiment of a heater 122 'of the present invention, (a) is a sectional view and (b) is a plan view. FIG.
FIG. 6 is a curve diagram showing the characteristic of the specific resistance ρ with respect to the composition ratio of Ni and Co. In FIG. 1 (a), the heater 122 'is
Similar to the conventional heater 122 shown in FIG. 3, it has two ceramic plates 1221a and 1221b, between which nickel Ni and cobalt Co are the main components and iron Fe or aluminum Al is added. Heating wire 1223 made of alloy
Sandwich. In FIG. 1 (b), the heating wire 1223
Is, for example, a strip having an appropriate width, which is arranged in a circle as shown in the drawing, and lead wires 1224a and 1224b are provided at the start and end thereof.
To connect to the AC power supply side. However, heating wire 1223
As a matter of course, a circular or square linear object may be used instead of the band plate.

The specific resistance ρ of the above alloy is Ni, Co, Fe
Alternatively, it changes depending on the Al composition ratio. Figure 2 shows Ni and Co
A qualitative characteristic curve of the specific resistance ρ with respect to the composition ratio (excluding Fe or Al) is shown, and the specific resistance ρ becomes the maximum value ρ _{m at a} certain value Q (golden composition ratio), and before and after that. Then, it decreases as shown. When Fe or Al is added, qualitatively the same characteristics are exhibited. Thereby, the composition ratio of the alloy is Ni (50-80%), Co (5
.About.20%), Fe or Al (5 to 10%), if set to an appropriate value and synthesized, an ingot with a specific resistance .rho. Is heated to form heating wire 1223.

The heater 122 'can be used not only in a plasma CVD apparatus but also in an etching apparatus that requires cleaning similar to the plasma CVD apparatus.

[0013]

As described above, the heater according to the present invention uses nickel Ni and cobalt C as heating wires.
o, an iron Fe or aluminum Al alloy is used, and the composition ratios thereof are appropriately set to have substantially the same specific resistance and workability as those of the conventionally used nichrome wire. It eliminates the deterioration or disconnection of the heating wire due to the halide generated at that time.
As a result, a reduction in the operating rate of the CVD apparatus is avoided, and a heating heater for replacement is not required, and the labor and cost of replacement can be saved. The effect of contributing to the plasma CVD apparatus is excellent. There is something.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a heater of the present invention, (a) is a sectional view and (b) is a plan view.

FIG. 2 is a curve diagram showing the characteristic of the specific resistance with respect to the composition ratio of Ni and Co.

FIG. 3 is a configuration diagram of a parallel plate type plasma CVD apparatus.

FIG. 4 is an explanatory diagram of a cleaning method of a plasma CVD apparatus.

[Explanation of symbols]

1 ... Plasma CVD apparatus, 11 ... Reactor, 111 ... Window, 112
… Door, 113… Outlet, 12… Susceptor part, 121… Insulating support, 122… Heating heater, 1221a, 1221b… Ceramic plate, 1222… Nichrome wire, 123… Soaking plate, 13… Shower electrode, 131… Injection hole , 14 ... Nozzle part, 141, 142 ... Inlet, 15 ... High frequency power supply part, 151, 152 ... High frequency oscillator, 12
2 '... heater of this invention, 1223 ... heating wire, 1224a, 122
4b ... Lead wire, 2 ... Wafer.

Claims (3)

[Claims] 1. A reaction gas injected from a shower electrode to a surface of a wafer to be processed heated to a predetermined temperature by a heater, and a high frequency voltage is applied to the shower electrode to inject the reaction gas. In a plasma CVD apparatus for forming a thin film on the surface of the wafer by using nickel Ni and cobalt Co as heating wires of the heater.
An alloy containing, as a main component, a metal material having a melting point of 200 ° C. or higher for a halide generated by the fluorine F-based gas when cleaning the inside of the CVD apparatus with the fluorine F-based gas. Plasma CVD
Heater for equipment. 2. The heater for a plasma CVD apparatus according to claim 1, wherein the metal material to be added is iron Fe or aluminum Al. 3. The alloys of nickel Ni and cobalt Co,
And the composition ratio of the alloy of iron Fe or aluminum Al to be added is Ni (50 to 80%), Co (5 to 20).
%), Fe or Al (5-10%) within the range,
The plasma CVD according to claim 1 or 2, wherein the specific resistance of the alloy is set to a value suitable for the heater.
Heater for equipment.