JPS5849016B2 - Diffusion holding jig - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a jig used for diffusing impurities into a semiconductor wafer, and in particular, a jig in which a plate-shaped impurity source containing impurities of a predetermined conductivity type and a semiconductor wafer are arranged facing each other. This relates to a holding jig for diffusion that is held by holding it upright.

Generally, in the diffusion process used for semiconductor integrated circuits, a certain amount of impurities is diffused onto the surface of a semiconductor wafer (pre-diffusion), and then the pre-diffused impurities are heat-treated in an impurity-free atmosphere. Usually, redistribution diffusion is performed to change the impurity distribution.

In this case, as the impurity source, a flat plate of BN (boron nitride), boron brass (main component B, 203: trade name), etc. is used for boron, and SiP207, etc. is used for phosphorus, and this impurity source and the semiconductor wafer are used. There is a method of diffusion by arranging one principal surface of the fluorophore and one main surface thereof facing each other and standing upright.

This method is widely used because the diffusion equipment, especially the impurity doping equipment, is simple.

However, in order to control the surface concentration of diffused impurities between the plate-shaped impurity source and the semiconductor substrate, the size interval between each plate is 1 to 3 m.
A holding jig with functions such as holding each impurity source and semiconductor wafer as close as possible at equal intervals, minimizing the holding portion of each impurity source and semiconductor wafer, and making it easy to insert and remove them. is required.

Conventionally, as shown in FIG. 1, such a holding jig is provided with a frame body 1 constructed by combining rod-like members with circular or square cross sections into a frame shape, and a frame body 1 is provided with an opposing surface of the frame body 1. 1, plate-shaped impurity sources and support grooves 2-, 2-5 and 3-1 to 3-4 for semiconductor wafers are arranged at equal intervals and corresponding positions along the longitudinal direction of the inner surface. It is well known that it is shaped like this.

Note that the plate-shaped impurity source is usually designed to have a larger diameter than the semiconductor wafer in order to prevent variations in diffusion, and is designed to have a larger diameter than the semiconductor wafer support grooves 3-1 to 3.
-4 is formed to be shallower and smaller in width than the support grooves 2-1 to 2- for the impurity sources, so that the center position of the support grooves 2-4 and the impurity sources substantially coincide with each other when stored.

Incidentally, after cleaning the plate-shaped impurity source as a pretreatment step, it is usually held in each of the support grooves z-1 to 2- of the holding jig in advance to protect it from moisture and contamination, and then placed at the opening of the diffusion furnace. Stored in a clean place such as

Therefore, when placing a large number of semiconductor wafers 6 between the plate-shaped impurity sources 5 held in advance as shown in FIG.
A similar operation is performed when inserting each semiconductor wafer 6 into wafers 1 to 3-4, or when taking out each semiconductor wafer 6.

However, in the conventional holding jig, each support groove 2
-1 to 2-, and 3-1 to 3-4 are formed on the same surface with relatively small dimensions, so it is difficult to insert a semiconductor wafer between the plate-shaped impurity sources held in advance. The removal work was extremely troublesome.

In the process of handling semiconductor wafers and casings, generally only the semiconductor wafers are stored in one basket, and the plate-shaped impurity source is stored in a clean place such as the mouth of the diffusion furnace as mentioned above. Therefore, it was troublesome to place them one after another.

Furthermore, in the conventional method, when performing redistribution diffusion after preliminary diffusion, it is necessary to take out each impurity source into separate jigs and perform the diffusion work, which is a disadvantage that the work is complicated and time-consuming. was there.

The present invention has been made to eliminate such conventional drawbacks, and by creating a separate structure for the holding member that holds the plate-shaped impurity source and the holding member that holds the semiconductor wafer, each impurity source can be separated. The purpose of the present invention is to provide a holding jig for diffusion that facilitates the work of inserting and taking out a source and semiconductor wafer, and also simplifies the work of redistribution and diffusion from preliminary diffusion.

EMBODIMENT OF THE INVENTION Hereinafter, this invention will be explained in detail based on an Example using drawing.

FIG. 2 is an exploded perspective view showing an embodiment of the holding jig according to the present invention.

In FIG. 2, 10 is a holding frame constructed by combining rod-like members made of non-porous quartz rods with a circular cross section into a frame shape;
Support grooves 11-1 to 11- are formed in the inner inner surface of the holding frame 10 at equal intervals and corresponding positions along the longitudinal direction.

Each of these support grooves 11-1 to 11- is configured to approximately match the circumference of the plate-shaped impurity source and to partially fit therein.

Reference numeral 12 denotes a holding stand made of a plate-like member made of polycrystalline silicon with a convex cross section, and a holding part 13 protruding from the center thereof has relief grooves 14-1 to 14-1 along the longitudinal direction.
14-, and support grooves 15-, to 15-4 are formed alternately.

In this case, each relief groove 14-1 to 14-14, . are provided corresponding to the support grooves 11-1 to 11-5 of the holding frame 10, and the width of each groove is equal to the width of the support grooves 11-1 to 11-,
The plate-shaped impurity source is configured to be larger than that and provided sufficiently deep so that the plate-shaped impurity source does not come into contact with it during insertion.

Each of the support grooves 15 to 15-4 is arc-shaped so as to be parallel to the escape grooves -1 to 14-5 and spaced apart from each other at regular intervals so as to substantially coincide with the outer periphery of the semiconductor wafer.

1, both ends 12a and 12b of the upper surface of the holding base 12 are provided with escape grooves 14-, 14-, 14-, 24-2, which are formed in the holding part 13 so that the pair of rod-shaped members 10a and 10b constituting the holding frame 10 can come into contact with each other.
14. and support groove 1! The width D of the holding portion 13 is
1 is formed to have a size somewhat smaller than the inner frame width D2 of the holding frame 10, and a holding frame 1o is fitted onto the holding table 12 so as to be detachable.

Next, the manner of use of the above-mentioned holding jig will be explained.

1. Using tweezers or the like, remove the plate-shaped impurity source 5 that has undergone a predetermined cleaning process through each of the support grooves 11-1 to 11- of the holding frame 10.
When these impurity sources 5 are respectively fitted, they are arranged facing each other at intervals determined by the respective supports 11-1 to 11-, and placed on the holding frame 10 in an upright state,
Wait for pre-diffusion.

Next, the semiconductor wafers . . . 6 which have undergone a predetermined cleaning process are similarly fitted into the support grooves 15-1 to 15-4 of the holding table 12, and are arranged facing each other and standing upright on the holding table 12. Leave it there.

Then, a pair of gripping tools 16a, 16b are engaged with the holding frame 10 as shown in FIG.
6b, the holding frame 10 is lifted up, and the lower part of the plate-shaped impurity source 5 placed on the holding frame 10 is placed on the holding stand 12 on which the semiconductor wafer 6 has been placed in advance. 14-1 to 14-, and the rod-like members 10a, 10b of the holding frame 10 abut against both ends of the upper surface of the holding frame 12, and the holding frame 10 is fitted. The table 12 and the holding frame 10 are integrally combined to form a holding jig as shown in FIG.
are arranged facing each other at equal intervals and placed in an upright state.

Thereafter, by placing such a holding jig in a diffusion furnace and performing heat treatment, a certain amount of impurities of a specific conductivity type contained in the plate-shaped impurity source 5 is precipitated on both sides of the opposing semiconductor wafer 6. It is crushed and the preliminary diffusion ends.

After this preliminary diffusion, when the holding frame 10 for the impurity source and the holding table 12 for the semiconductor wafer are separated by the operation opposite to that described above, only the semiconductor wafer 6 is placed on the holding table 12. By placing this holding table 12 in a diffusion furnace with an atmosphere that does not contain impurities, redistribution diffusion can be performed.

As described above, according to the present invention, since the plate-shaped impurity source and the semiconductor wafer can be inserted and removed using the independent holding frame 10 and holding stand 12, the work is very easy, and Since the holding frame 10 and the holding stand 12 can be integrated by fitting together, they can be easily attached and detached.

Furthermore, when redistributing and diffusing after the completion of preliminary diffusion, it is only necessary to separate the holding frame 10 and the holding table 12, without having to take out the plate-shaped impurity sources one by one and place only the semiconductor wafer. The process can be simplified.

In addition, in the above embodiment, the holding stand 12 for semiconductor wafer...
The arc-shaped support grooves 15-1 to 15-4 formed in the escape grooves 14, -. 14- and 14-, in other words, the case where pre-diffusion is performed on both sides of the semiconductor wafer, the present invention provides a method for pre-diffusion on only one side of the semiconductor wafer. It is also applicable to a method in which two semiconductor wafers are placed close to a plate-shaped impurity source and their main surfaces face each other without pre-diffusion, that is, two arc-shaped support grooves are provided for simultaneous pre-diffusion of two semiconductor wafers. You can also do that.

Furthermore, in the above embodiment, a case is shown in which a plate-shaped impurity source is placed on the holding frame 10 and a semiconductor wafer is placed on the holding table 12, but these may be applied in place of each other.

In this case, each escape groove and support groove formed in the holding table for the impurity source may be formed in a shape corresponding to a semiconductor wafer or a plate-shaped impurity source.

Furthermore, the material of each holding frame 0 and holding stand 12 is not limited to quartz or polycrystalline silicon, but may be any other material such as silicon carbide or ceramic that is heat resistant and does not react easily to chemicals. Of course.

As explained above, according to the holding jig according to the present invention,
It is possible to easily insert and take out each impurity source and the semiconductor wafer, and it is also possible to simplify the work from pre-diffusion to redistribution diffusion.

[Brief explanation of drawings]

Figure 1 is a perspective view for explaining a conventional holding jig, Figure 2 is a perspective view for explaining a conventional holding jig;
The figure is an exploded perspective view showing one embodiment of the holding jig according to the present invention, and FIG. 3 is a perspective view of its assembled state. 5... Plate-shaped impurity source, 6... Semiconductor wafer, 10... Holding frame, 11-1 to 11-5
......Support groove, 12...Holding stand, 13.
...Holding portion, 14-1 to 14-5...Escape groove, 15-1 to 15-4...Support groove.

Claims (1)

[Claims] 1. In a holding jig that holds a plate-shaped impurity source and a semiconductor wafer by arranging them facing each other and standing them upright, rod-shaped members are combined into a rectangular frame shape, and the longitudinal sides of the opposing inner surfaces of the members are assembled. A holding frame having support grooves formed at equal intervals along the direction so as to be able to fit a plate-shaped impurity source or a part of the semiconductor wafer, and a cross-section having a convex shape on the upper surface of the plate-shaped member. and a holding base that is detachably attached to the holding frame by fitting the holding part into the frame of the holding frame, The holding part has a relief groove provided corresponding to the support groove of the holding part and an arc-shaped support groove provided approximately to the outer periphery of the semiconductor wafer or the plate-shaped impurity source that is not located in the relief groove. A holding jig for diffusion characterized by the following configuration.