JPH04364028A - Heat treatment - Google Patents

Abstract

PURPOSE:To supply gas without interruption and to make the time required for heat treatment uniform by using a heating tube having a uniform inner diameter and by supplying gas from an opening of a pipe placed opposite to the semiconductor carrier inserting or taking out side when the semiconductor carrier is inserted or taken out. CONSTITUTION:A silica cap 3 can be set on a fitting part provided at each end of a silica tube 1 having a uniform inner diameter. With a mixed gas of nitrogen and oxygen 8 being supplied from a gas lead-in pipe 9 having a flange part 91 to be matched with a flange part 31 at the end of the cap 3 into the inside of the silica tube 1 which has been heated to high temperature by a heating wire 2, the cap 3 of the silica tube 1 is removed and a boat 5 on which silicon substrates 4 are set is carried to the central part of the silica tube 1 from the cap-removed side, using an automatic loader. After that, the removed cap 3 is mounted again and the mixed gas 8 is supplied from a gas lead-in pipe 6 on the other side and the silicon substrates 4 are heat-treated and then a cap 3 which is on the side of the gas lead-in pipe 6 is removed for taking out the boat 5 through an opening at the side of the gas lead-in pipe 6, using the automatic loader.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention involves housing a semiconductor element in a heating tube heated to a high temperature for the purpose of diffusing impurities into the semiconductor element, for example, and heating the semiconductor element at a high temperature for a predetermined time while passing gas through the heating tube. The present invention relates to a heat treatment method for heating to .

0002

[Prior Art] In semiconductor technology, impurity diffusion,
It is well known that in many processes such as oxide film formation, epitaxial growth, and annealing, a semiconductor element is heated in a gas stream to a predetermined temperature for a predetermined time in a heat treatment furnace. Figure 2 shows a diffusion furnace used in the conventional diffusion process, in which a quartz tube 1 has a heating wire 2 wound around its center.
Inside the quartz tube 1, the cap 3 fitted at the joint at one end of the quartz tube 1 is removed, and a boat 5 with a plurality of silicon substrates 4 on the surface of which has been previously coated with a film containing impurities is inserted into the slit. be able to. The other end of the quartz tube 1 is squeezed, and the flange 61 at the end of the gas introduction tube 6 is brought into close contact with the flange 11 at the tip using scissors 7, thereby connecting the quartz tube 1 and the gas introduction tube 6. do.

When performing diffusion, the heating wire 2 lowers the temperature to 1
Into the quartz tube 1 heated to 000 to 1200°C, nitrogen is introduced from the gas introduction pipe 6 at a flow rate of, for example, 2 liters/min and 0.000°C.
While supplying a mixed gas 8 with oxygen at a flow rate of 5 liters/minute, insert the boat 5 with the silicon substrate 4 set into the quartz tube 1 through the tube opening from which the cap 3 has been removed.
After the cap 3 is attached and the gas is exhausted from the hole 32 of the cap for 3 to 5 minutes to diffuse impurities into the silicon substrate 4, the cap 3 is removed again and the boat 5 is taken out.

In the conventional diffusion method shown in FIG. 2, a boat 5 on which a silicon substrate 4 is set is loaded into and taken out of a quartz tube 1 using an autoloader. However, in this case, it takes 3 to 5 minutes each time to take the boat in and out. For this reason,
The heat treatment time varies depending on the position of the silicon substrate 4 on the boat. In other words, the heat treatment time is longer for substrates located on the upstream side of the gas, far from the entrance/exit of the boat, and the heat treatment time is longer for substrates located on the downstream side.
It will be 0 minutes shorter. This means that, for example, when the accuracy of the Zener voltage is required to be within 2%, as in the case of a silicon substrate for a Zener diode, the Zener voltage may be 0.0
Since the voltage varies by 4 to 0.08V, it means that the accuracy requirement cannot be met, and the rate of non-defective products decreases.

[0005] In order to eliminate such variations in heat treatment time, a boat is inserted from one side of the diffusion furnace at a high temperature.
If you take it out from the other side, even if it takes time to put it in and take it out of the furnace, the silicon substrates at one end of the boat stay in the furnace the same time as the silicon substrates at the other end, and uniform heat treatment can be achieved. be able to. However, in order to insert the boat from one end of the quartz tube and take it out from the other end, it is not possible to use a quartz tube with a reduced diameter at one end as shown in Figure 2, and a quartz tube with a uniform inner diameter must be used. Must be. It is impossible to insert a boat into such a quartz tube with gas flowing, and the atmosphere inside the tube changes upon insertion, changing the surface condition of the silicon substrate.

An object of the present invention is to solve these problems and provide a heat treatment method in which the atmosphere does not change during the heat treatment and the heat treatment time does not change depending on the position of the semiconductor element.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention increases the temperature inside a heating tube having a uniform inner diameter, and then introduces a gas from a gas introduction tube connected to a pipe port at one end of the tube. While supplying gas into the tube, a support body carrying multiple semiconductor elements is inserted into the tube from the open tube port at the other end, and then a gas introduction tube is connected to the tube port at the other end to supply gas into the tube. The semiconductor element is heated for a predetermined period of time by switching the supply from the introduction tube, and then the support is taken out from the open tube opening at one end of the heating tube. Alternatively, after increasing the temperature inside a heating tube with a uniform inner diameter, gas is supplied into the tube from a gas introduction tube connected to one end of the tube, and multiple semiconductor elements are supplied from the open tube port at the other end. After inserting the supporting body equipped with the heating tube into the tube and heating the semiconductor element for a predetermined time, the gas supply is switched to the gas introduction tube connected to the port at the other end of the heating tube, and the port at one end is opened. Then, the support is taken out from the pipe port. In either method, it is effective to connect the gas introduction pipe to the pipe port via a connecting pipe that fits into the fitting portions formed at both ends of the heating pipe.

[0008]

[Operation] Using a heating tube with a uniform inner diameter, when inserting the support for the semiconductor element through one open tube opening, gas is supplied from the gas introduction tube connected to the other tube opening, and the support is heated. At the time of extraction, gas is being supplied from the gas introduction pipe connected to one pipe port, and gas is being taken out from the other pipe port, and if gas is supplied from either gas introduction pipe in the middle, the same gas is always supplied. Insertion, heat treatment, and removal of the semiconductor element are performed in an atmosphere, and since insertion is performed from one side of the heating tube and removal from the other side, there is no variation in heat treatment time.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a diffusion furnace used in an embodiment of the present invention, and parts common to those in FIG. 2 are given the same reference numerals. In this case, the quartz tube 1 has a uniform inner diameter, and the quartz cap 3 can be sandwiched between the mating portions on both sides. Inside the quartz tube 1 heated to 1000 to 1200° C. by the heating wire 2, there are gas introduction tubes 9 to 2 having a flange portion 91 that is brought into contact with the flange portion 31 at the tip of the cap 3 on the right side of the diagram of the quartz tube 1. While supplying a gas mixture 8 of nitrogen at a flow rate of l/min and oxygen at a flow rate of 0.5 l/min, the cap 3 on the left side of the diagram of the quartz tube 1 is
is removed, and from that side, using an autoloader, the boat 5 on which the silicon substrate 4 is set is slowly fed into the center of the quartz tube 1. Thereafter, the removed cap 3 is attached, and the supply of the mixed gas 8 is switched to the gas introduction pipe 6 whose flange 61 is brought into contact with the flange 31 using scissors 7.
After heat treatment in that state for a minute, the cap 3 is removed and the boat 5 is taken out from that side using an autoloader.

In another method, gas is continued to be supplied from the gas introduction pipe 9 during the heat treatment, and just before taking out the boat 5, the gas supply is switched to the gas introduction pipe 6, the gas introduction pipe 9 is removed from the cap 3, and the cap is removed. 3 from the quartz tube 1 and pull out the boat 5 to the right side of the figure. When silicon wafers for Zener diodes are subjected to diffusion heat treatment using these methods, the junction depth, which determines the Zener voltage, can be made nearly uniform, improving the yield rate.

[0011]

[Effects of the Invention] According to the present invention, a heating tube with a uniform inner diameter is used, and when a semiconductor element support is inserted or removed, the gas supply is interrupted by supplying gas from the opposite tube opening. Since the semiconductor element is moved in one direction in the heating tube in a constant atmosphere, the heat treatment time becomes uniform. It was done. Therefore, it can be very advantageously applied to heat treatment that has a large effect on heat treatment time characteristics, such as impurity diffusion for manufacturing Zener diodes, for example.

[Brief explanation of the drawing]

[Fig. 1] Cross-sectional view of a diffusion furnace used in one embodiment of the present invention

[Figure 2] Cross-sectional view of a conventional diffusion furnace

[Explanation of symbols]

1 Quartz tube 2 Heating wire 3 Cap 4 Silicon substrate 5 Boat 6 Gas introduction pipe 8 Mixed gas 9 Gas introduction pipe

Claims (3)

[Claims] Claim 1: After increasing the temperature inside a heating tube with a uniform inner diameter, gas is supplied into the tube from a gas introduction tube connected to a port at one end of the tube, and then from an open port at the other end. A support body carrying a plurality of semiconductor elements is inserted into the tube, then a gas introduction tube is connected to the tube port at the other end, and the gas supply into the tube is switched from the gas introduction tube to place the semiconductor elements in a specified position. A heat treatment method characterized by heating for a period of time and then taking out the support from an open port at one end of a heating tube. Claim 2: After increasing the temperature inside a heating tube having a uniform inner diameter, gas is supplied into the tube from a gas introduction pipe connected to a port at one end of the tube, and from an open port at the other end. A support body carrying a plurality of semiconductor elements is inserted into the tube, and after heating the semiconductor elements for a predetermined period of time, the gas supply is switched to the gas introduction pipe connected to the port at the other end of the heating tube, and one end is heated. A heat treatment method characterized by opening a pipe port and taking out the support from the pipe port. 3. The heat treatment method according to claim 1, wherein the connection of the gas introduction pipe to the pipe port is carried out through a connecting pipe that is fitted into fitting portions formed at both ends of the heating pipe.