JPS61172325A - Vertical type heat treating furnace - Google Patents

Abstract

PURPOSE:To prevent a wafer from contacting to the inner wall of a furnace as wel as to enable to reduce the generation of foreign matters by a method wherein a vertical type constitution, in which the space where the material to be treated is present almost along vertical direction, is provided. CONSTITUTION:A space in which a wafer retainer 12 will be inserted is ar ranged in the vertical direction. A number of wafers 11 held in the wafer retain er 12 are inserted in a vertical type diffusion furnace (heat treating furnace) 13 in almost horizontal state by holding the wafers in a jig holder 16 and rotat ing the jig 12 at an angle of 90 degree. The diffusion furnace 13 has a heater 14, and the carrier gas 15 containing impurities is introduced from the lower side. A diffusion treatment is performed by introducing gas 15 into the furnace 13 and the wafers 11 are heated up to the prescribed temperature using the heater 14. On the other hand, the wafer retianing jig 12 is maintained in the state wherein it does not come in contact with the inner wall of the furnace using the jig holder 16.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an apparatus for performing heat treatment such as impurity diffusion on a semiconductor wafer.

[Background Art] Conventionally, when diffusing seven receptor impurities or donor impurities into semiconductor wafers, a large number of wafers 1 are held upright in a jig 2 made of quartz or silicon and held in parallel, as shown in FIG. However, it is generally inserted into a horizontal diffusion furnace 3 as shown in FIG.
and a carrier gas containing impurities (02 = H2 = N2, etc.) from the end opposite to the wafer insertion opening.
It was normal that 5 was allowed to flow in. An example of a horizontal diffusion furnace is JP-A-49-104570.

However, according to such conventional techniques, when a wafer is inserted into a furnace, the inner wall of the furnace body and the wafer jig tend to come into contact with each other, resulting in the generation of foreign matter. In addition, due to uneven temperature distribution in the furnace, uneven gas flow velocity distribution, or turbulent flow, considerable variations in device characteristics occur within a wafer or between wafers. There is.

In other words, when the wafer is held in the furnace, the wafer jig comes into contact with the wall of the furnace, so heat transfer from this contact surface may cause a difference in temperature distribution between the wafer jig and the wafer, or heat may be introduced into the furnace. There is a problem in that the density of the reactant gas generated differs between the upper and lower parts of the furnace body due to the influence of gravity, and variations occur within a single wafer.

Furthermore, it is not suitable for automation as it is necessary to replace the wafer with a jig one by one. Another disadvantage is that the device occupies a considerable amount of space.

[Object of the Invention] An object of the present invention is to provide a new heat treatment furnace that eliminates the above-mentioned drawbacks.

[Summary of the Invention] A typical outline of the present invention is as follows. In other words, the apparatus has a vertical configuration in which the space into which the object to be processed is inserted exists substantially along the vertical direction.

With such a configuration, the inner wall of the furnace and the wafer (wafer jig) can be made non-contact, and the generation of foreign matter can be reduced. In addition, since the wafer is held almost horizontally, it is easy to transfer the wafer from one jig to another in a batch, making it compatible with automation and also compatible with larger diameter wafers.

Furthermore, it saves space and energy, and is resistant to thermal deformation.

[Embodiment] FIG. 3 shows a wafer holding jig used in an embodiment of the present invention, in which a large number of semiconductor wafers 11 are held at approximately equal intervals by a pair of upper and lower holding members 12A.

They are arranged in a holding jig 12 consisting of 12B. The holding members 12A and 12B have the same configuration as each other, and are formed by a total of six rod-shaped parts 12X, each having three cylindrical parts each having an inner diameter corresponding to the outer diameter of wa/% when stacked as shown in the figure. It is supposed to be done.

A groove with a width corresponding to the wafer thickness is cut in the portion of each rod-like portion 12X that should engage the wafer 11, so that the wafer does not fall even when the wafer 11 is held horizontally as described later. It has become.

A large number of wafers 11 held in the wafer holding jig 12 as shown in FIG.
By rotating it by 0° and holding it in the jig holder 16, it is inserted into the vertical diffusion furnace (heat treatment furnace) 13 in a substantially horizontal state. The diffusion path 13 has a heater 14 and is adapted to introduce a carrier gas 15 containing impurities from below.

In the diffusion process, a gas 15 is introduced into the furnace 13 and the wafer 11 is heated to a predetermined temperature by the heater 14. On the other hand, the wafer holding jig 12 is held using a jig holder 16 without contacting the inner wall of the furnace. In this embodiment, by utilizing this non-contact, the jig holder 16 is
By moving the wafer 11 up and down as shown in FIG. 2 and rotating it as shown by arrow R, the wafer 11 is given vertical movement and rotational motion. In this way, the heat of the heater 14 can uniformly affect the impurities in the wafer 15 on the wafer 111, so that variations in device characteristics within a wafer and between wafers can be significantly reduced.

5 and 6 show that when a large number of diffused transistors are formed on each wafer in the processing batch of FIG. 4,
The variation in current amplification factor hp+= of transistors within one wafer or between a plurality of wafers is shown in comparison with the conventional method.

According to FIG. 5, it is clear that the variation in hpg along the Y direction within one wafer 11 is much smaller in the case of the present invention shown by the solid line B than in the case of the conventional method shown by the broken line A. . Furthermore, according to FIG. 6, it is clear that the variation in hpI: between wafers 11 within the same processing batch is sufficiently smaller in the case of the present invention shown by the solid line B than in the conventional case shown by the broken line A. be.

[Effect J] As described above, by using a vertical heat treatment furnace, it is possible to significantly reduce variations in device characteristics within and between wafers without complicating the furnace structure or the jigs used. , various semiconductor devices can be manufactured with high yield.

Furthermore, since the inner wall (quartz) of the furnace and the wafer jig do not come into contact with each other, the generation of foreign matter is reduced.

In addition, there is no need to stand the wafer vertically, and if the jig is designed, it is possible to transfer the wafers from one jig to another at once, making it suitable for automation.

Furthermore, it is easy to handle large diameter wafers.

In addition, since the vertical space that has not been used in the past is effectively utilized, the dedicated space can be significantly reduced. In addition, it is highly efficient and saves energy.

In addition, in a horizontal furnace, if the furnace body is kept at a high temperature for a long time, deformation such as the central part of the quartz tube sagging downwards due to the influence of gravity is likely to occur, but in a vertical furnace, the quartz tube originally sag in the direction of gravity ( Since it extends in the vertical direction, there is less worry about deformation such as sagging.

[Application field] The present invention is very effective as a heat treatment apparatus.

[Brief explanation of the drawing]

FIG. 1 is a side view showing how a wafer is held in a conventional technique, FIG. 2 is a sectional view of a furnace showing a diffusion method in a conventional technique, and FIG. 3 is a wafer holding fixture used in an embodiment of the present invention. FIG. 4 is a sectional view of a furnace showing a diffusion method according to an embodiment of the present invention, and FIGS. 5 and 6 are graphs showing the effects of the present invention in comparison with the conventional technique. It is. 11... Semiconductor wafer, 12... Wafer holding jig,
13... Vertical diffusion furnace, 16... Jig holder. Figure 1 Figure 2 Figure 6

Claims (1)

[Claims] A vertical heat treatment furnace having a furnace body in which a space into which a workpiece is inserted runs substantially vertically.