JPH0738379B2 - heating furnace - Google Patents

Description

TECHNICAL FIELD The present invention relates to a heating furnace used for semiconductor wafer diffusion, CVD, oxidation treatment, and the like.

[Conventional technology]

Conventionally, heating furnaces used for diffusion processing of semiconductor wafers are
As shown in FIG. 3, a cylindrical heater 2 is arranged on the outer circumference of a quartz tube 1 constituting a furnace body, and the heater 2 is divided into a center zone B and end zones A and C on both sides thereof. First and second intermediate terminals 3 and 4 are provided, and these intermediate terminals 3 and 4 and both ends 5 and 6 of the heater 2 are connected to the secondary side of the three-phase transformer 7 as shown in the wiring diagram of FIG. It has been configured. Reference numeral 8 in FIG. 4 is a thyristor for current control.

For example, when performing diffusion using such a heating furnace,
As shown in FIG. 3, a large number of semiconductor wafers 9 are mounted on a quartz board.
The semiconductor wafer 9 is placed on the quartz tube 1 and inserted into the quartz tube 1, and the semiconductor wafer 9 is heated by the heater 2. At the same time, a carrier gas is flown in the quartz tube 1 as shown by an arrow to form a diffusion layer on the surface of the semiconductor wafer 9. I am trying.

[Problems to be solved by the invention]

In such a conventional heating furnace, since the heater 2 and the three-phase transformer 7 are connected as shown in FIG. 4, the first and second intermediate terminals 3 and 4 and the three-phase transformer 7 are connected. The magnitudes of the currents I ₁ and I ₂ flowing through the cables 11 and 12 are larger than the currents I _A , I _B and I _C flowing through the zones A, B and C of the heater 2 as shown in the vector diagram of FIG. There is a drawback in that a cable that is large and has a large cross section must be used.

The present invention has been made to solve such a problem, and an object thereof is to use a cable having a small cross-sectional area as a cable connecting an intermediate terminal of a heater and a power supply source. It is to provide a heating furnace that can.

[Means for solving problems]

In order to solve the above problems, the present invention is characterized by inverting the phase of the current flowing through the center zone of the heater or the end zones on both sides by 180 °.

[Action]

In the present invention, the magnitude of the current flowing through the cable connecting the intermediate terminal of the heater and the three-phase transformer is reduced by shifting the phase of the current flowing through the center zone or both end zones of the heater by 180 °. You can

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. The same parts as those in FIG. 4 are designated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 is a diagram corresponding to FIG. 4, and is a circuit diagram showing a connection relationship between the heater 2 and a three-phase transformer 7 which is a power supply source. In this embodiment, a plurality of intermediate terminals, for example, first and second intermediate terminals 3 and 4 are connected to one ends of the first and third secondary windings 13 and 15 of the three-phase transformer 7, respectively, and three-phase The second secondary winding 14 of the transformer 7 is connected to the second secondary winding 14 with its phase changed from the conventional one, for example, with its polarity reversed (180 ° phase changed). Both ends 5 and 6 of the heater 2 are connected to the other ends of the first and third secondary windings 13 and 15 as in the conventional case.

In this way, by connecting the first and second intermediate terminals 3 and 4 to the second secondary winding 14 of the three-phase transformer 7 with the polarity reversed from the conventional one, the center zone B of the heater 2 is Since the phase of the flowing current I _B is shifted by 180 °, that is, inverted, the first and second intermediate terminals 3 and 4 and the three-phase transformer 7 are connected as shown in the vector diagrams of FIGS. 2 (a) and 2 (b). Cable 11,12
It is possible to reduce the magnitudes of the currents I ₁ and I ₂ flowing through.

The currents I ₃ and I ₄ flowing through the intermediate terminals 3 and 4 by the connection in FIG. ₄ are respectively In contrast to the above current, the currents I ₃ and I _{4 in} the case of FIG. Current flows.

Therefore, the current flowing through I ₃ and I ₄ in this embodiment is I
_A current of _A or I _B or less flows. Therefore, the connection line between the intermediate terminal and the power supply source can be a current line that is thin.

Next, the configuration will be specifically described with reference to FIG.

The drive circuit of the cylindrical heater 2 provided so as to surround the reaction tube 1 as shown in FIG. 3 is as shown in FIG.

The heater 2 is divided into a plurality of parts, and the heater coil is continuously and integrally formed as shown in FIG. That is, it is divided into a desired plurality, for example, three divisions. This division is divided into a center zone B and end zones A and C. Each zone A, B, C is divided into intermediate terminals 3, 4
Is drawn out to a predetermined position of the heater coil 2. An output of a power supply source, for example, a three-phase transformer 7 to which a heating current is supplied, is connected to the terminals 3 and 4 and the terminals 5 and 6 of the end zone through a current control thyristor 8.

Here, the currents flowing in the zones A, B, C have different phases in the adjacent zones. For example, they are 180 degrees out of phase. As means for this, in the three-divided zone, the wiring of the center zone B is connected in reverse to the wiring of the adjacent zone.

By wiring in this manner, the current flows through the center zone B with a half cycle behind the end zones A and C. Here, since the temperature distributions formed by the zones A, B, C are different, the amount of electric power supplied from the three-phase transformer 7 is naturally different. This control is based on the three-phase transformer 7 described above.
The control is performed by the primary side provided for each. Fine temperature control by the control on the primary side is performed by the gate of the current control thyristor 8 provided in each zone A, B, C.

In this way, the drive circuit of the heater 2 is configured.

The present invention is not limited to the above embodiment.
For example, in the above embodiment, the center zone B of the heater 2 is
The phase of the current I _B flowing through the
Of the currents I _A and I _C flowing through the end zones A and C of
° May be reversed.

〔The invention's effect〕

As described above, according to the present invention, since the magnitude of the current flowing through the cable connecting the intermediate terminal of the heater and the three-phase transformer can be reduced, the intermediate terminal of the heater and the three-phase transformer are connected. A cable with a small cross-sectional area can be used for the cable, and the cost can be reduced.

[Brief description of drawings]

1 and 2 are diagrams showing an embodiment of the present invention. FIG. 1 is a circuit diagram showing a connection relationship between a heater and a three-phase transformer according to the present invention, and FIGS. 2 (a) and (b) are A vector diagram showing the magnitude of the current flowing in the cable connecting the intermediate terminal of the heater and the three-phase transformer in the embodiment, FIGS. 3 to 5 are diagrams showing a conventional example, and FIG. FIG. 4 is a schematic cross-sectional view, FIG. 4 is a circuit diagram showing the connection relationship between a conventional heater and a three-phase transformer, and FIG. 5 is a diagram showing the magnitude of current flowing in a cable that connects the intermediate terminal of the heater and the three-phase transformer. It is a vector illustration. 1 ... Quartz tube, 2 ... Heater, 3,4 ... Intermediate terminal, 7 ... Three-phase transformer, 8 ... Thyristor, 9 ... Semiconductor wafer, 10 ... Quartz boat, 11, 12 ... Cable, 1
3,14,15 …… Secondary side winding.

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Claims (1)

[Claims] 1. A heater disposed around a furnace body is provided with first and second intermediate terminals for dividing the heater into at least a center zone and end zones on both sides thereof, and these intermediate terminals and heaters. In a furnace with both ends connected to both sides of a three-phase transformer, the phase of the current flowing through the center zone or both end zones of the heater
A heating furnace characterized by being inverted by 0 °.