JPS63299230A - Heat treatment furnace - Google Patents

Abstract

PURPOSE:To manufacture a heat treatment furnace not to form an oxide film on the surface of a semiconductor sheet by a method wherein an equalizer in specified length is formed in the central part; a semiconductor conveyor continuously passing through at specified speed as well as a gas vent to a through hole are provided; and the difference between the temperature in the parts near both openings of the through hole and the room temperature is specified. CONSTITUTION:A heater 2 is arranged in the central part in length of 2 m around a heat resistant furnace core tube 1 within a furnace body 3, e.g., of 5 m in full length. When, after forming an equalizer 12 on the central part by supplying the heater with power within the furnace core tube 1 kept in reduced atmosphere, a jig 6 with a silicon sheet 5 Ni plated outside an inlet 11 is mounted on a belt conveyor 7 moving in the arrow 71 direction, the silicon sheet 5 is carried into the furnace. The in-furnace temperature is at 700 deg.C in the central equalizer 12 while nearly at the room temperature of 25 deg.C both at the point A near the inlet 11 and the point D near the outlet 13. In such a constitution, a semiconductor sheet heat treated as specified is to be exposed to the atmosphere only after passing through the part near the opening at the temperature making difference from the room temperature not exceeding 10 deg.C so that the surface of the semiconductor sheet may not be oxidized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention heats a silicon plate plated with N1, for example, and alloys silicon and N1 to form a surface with good brazing properties on the silicon plate surface. The present invention relates to a heat treatment furnace sometimes used for manufacturing semiconductor devices.

[Conventional technology]

In order to form a solderable bridge film on the surface of a silicon plate with a PN junction formed inside, Ni plating is applied to the surface of the silicon plate, but adhesion is weak if only a Ni plating layer is applied. In the later assembly process, the Ni layer separates from the silicon surface. Therefore, in order to improve the adhesion between the silicon and the former, heat treatment is performed to alloy the silicon and Ni. Conventionally, this heat treatment was performed as shown in Figure 2. This was carried out using a heat treatment furnace used for impurity diffusion into semiconductors as shown in Figure 1.

This furnace is equipped with a furnace body 3 having a heater 2 around a furnace core tube 1 made of quartz, as shown in FIG. 2(♂). During the heat treatment, as shown in FIG. This is a method in which the material is pushed to a soaking section 12 in the center of the furnace at a predetermined temperature, heat-treated for a predetermined time, and then taken out from the furnace mouth 11 again.

Inert or reducing gas is introduced into this furnace through the opening at the tip of the remaining quartz cap 4 to prevent the surface of the Ni layer of the silicon plate 5 in the soaking section 12 from being oxidized.

[Problem that the invention seeks to solve]

However, since the furnace mouth 11 is open, the silicon plate 5 pulled out from the soaking section 12 is exposed to the atmosphere at a high temperature. Then, since an oxide film is formed on the Ni surface, there is a problem that the adhesive strength of the solder decreases in the subsequent brazing.

In order to solve this problem, a silicon plate is set in advance at room temperature in the furnace core tube 1 which is in a reducing atmosphere, the temperature inside the furnace is raised to a predetermined temperature, heat treatment is performed for a predetermined time, and then the temperature of the furnace is One possible method is to cool the temperature to near room temperature and then remove the silicon plate. However, this method requires a long time for the furnace to heat treat a limited number of silicon plates, and it is necessary to spend a lot of time or increase the number of furnaces to heat treat a large number of silicon plates. Therefore, it was not realistic.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a heat treatment furnace suitable for performing heat treatment without forming an oxide film on the surfaces of a large number of semiconductor boards.

Means for Solving the Problem c] In order to achieve the above object, the heat treatment furnace of the present invention is provided with a soaking section of a predetermined length in the central part of the furnace body in the longitudinal direction,
It is equipped with a semiconductor board conveying means that passes continuously through a through hole in the core of the reactor body at a predetermined speed and a gas vent into the through hole, and the difference between the temperature near both openings of the through hole and room temperature is The temperature shall be within 10°C.

[Effect]

In the above-mentioned heat treatment furnace, the semiconductor board is passed through the through-hole by a conveying means while sending an inert or reducing gas into the through-hole, and the passage time through the soaking section is adjusted to the required heat treatment time. After the specified heat treatment, the semiconductor board is exposed to the outside air only after passing through the vicinity of the opening where the difference from room temperature is within 10°C, so the surface will not be oxidized. Since it is possible to send in heat treatment for a large number of semiconductor boards, it is possible to easily heat treat a large number of semiconductor boards.

〔Example〕

FIG. 1 shows an embodiment of the present invention, and parts common to those in FIG. 2 are given the same reference numerals. The furnace body 3 has a total length of, for example, 5 m, and a heater 2 is provided around the heat-resistant furnace core tube 1 at a distance of 2 m from the center.

Inside the furnace core tube 1 is a belt conveyor 7 made of heat-resistant material.
is understood. From the vent (not shown) to the furnace core tube 1,
It is possible to send a reducing gas such as a mixed gas of gas, H, and gas, and furthermore, it is possible to blow out a gas such as an inert gas at the furnace port 11.13 to prevent outside air from entering the furnace tube. .

Now, the inside of the furnace core tube 1 is made into a reducing atmosphere, and after the heater 2 is energized to form a uniform heating section 12 in the center, Ni plating is applied outside the furnace mouth 11 on the belt conveyor 7 moving in the direction of the arrow 71. When the jig 6 with the silicon plate 5 set thereon is placed, the silicon plate 5 is transported into the furnace. FIG. 3 shows the temperature bones and cloth in the furnace, and the positions A, B, C, and D in the furnace correspond to the positions marked in FIG. 1.

The temperature inside the furnace is 700°C, which is the heat treatment temperature in the central soaking section 12.
The room temperature at point A near population 11 and point D near exit 12 is close to 25°C. Therefore, the temperature of the silicon plate 5 rises from point A, where the atmosphere is completely reduced, and reaches a predetermined temperature at point B after about 30 minutes. The temperature of the silicon plate 5, on which the alloying of N1 and silicon has been completed by the heat treatment, decreases from point C, and after about 30 minutes, reaches approximately room temperature at point D in the reducing atmosphere near the outlet 12.

Therefore, the Ni surface of the silicon plate 5 can be prevented from being oxidized since it is exposed to the atmosphere after reaching approximately room temperature in a completely reducing atmosphere.

(Effects of the Invention) According to the present invention, a conveying means for passing a semiconductor board through a through hole maintained in an inert or reducing atmosphere in a furnace body is provided, and the temperature inside the through hole is maintained at both openings. By changing the temperature from within 10 degrees Celsius with the surrounding room temperature to a predetermined temperature in the central heating section, the semiconductor board being transported is heated from around room temperature without being exposed to the outside air, and heat treatment is performed to a predetermined temperature. Therefore, when an N1-plated silicon plate is heat-treated, an oxide film will not be formed on the Ni surface, so it will be easier to use when brazing the Ni1i electrode film and the contact conductor. The adhesive strength of the semiconductor board is improved, and defects in brazing are prevented. Similar effects can also be obtained during other heat treatments of semiconductor boards.Furthermore, in the heat treatment furnace according to the present invention, the semiconductor board is transported by means of conveyance means. Since it is possible to automatically feed a large number of semiconductor boards and process a large number of semiconductor boards continuously, high productivity can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2(a). (b) is a sectional view showing a conventional heat treatment furnace and the heat treatment operation therein, and FIG. 3 is a temperature distribution diagram of the heat treatment furnace shown in FIG. 1. 1: Furnace core tube, 2: Heater, 3: Furnace body, 7: Belt conveyor. -m-・81
Figure 112 Figure 3

Claims (1)

[Claims] 1) A soaking section of a predetermined length is provided in the longitudinal center of the furnace body, and a semiconductor board conveying means that continuously passes through a through hole in the core of the furnace body at a predetermined speed and gas into the through hole are provided. 1. A heat treatment furnace comprising a vent, wherein the temperature difference between the temperature near both openings of the through hole and room temperature is within 10°C.