JP2000331948A - Plate for diffusing boron - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate deformation for making uniform the diffusion concentration of boron and at the same time, achieving a plate to be capable of reproduction by depositing boron by such means as sputtering on the surface with a substance of higher melt point than a reactor core tube used for diffusion as a nucleus. SOLUTION: In a plate 3, a boron nitride 2 is deposited on a substance 1 with a higher melting point than a reactor core tube 7 through sputtering. Then, a silicon substrate is erected in parallel on a crystal port, while sandwiching the plate 3 where a boron oxide layer is formed by oxidizing the surface using an oxidation process as in a conventional method and is heated to diffuse boron into a silicon substrate. The plate 3 cannot be deformed, due to diffusion only by the conventional boron nitride 2 based on the above method. Therefore, it becomes possible to perform diffusion for coping with heating for a long time at high temperatures, thus reducing the scattering of the concentration of the diffusion of boron. Also, the boron nitride 2 can be deposited again through sputtering.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improvement in a plate used for performing boron diffusion in a semiconductor manufacturing process.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, a boron nitride (BN) plate 2 having a boron oxide layer 4 formed on its surface by an oxidation step is sandwiched in a furnace tube 7 used for boron diffusion. The silicon substrate 5 is set up in parallel on the quartz boat 6 with
Boron nitride (BN) plate 2
Deposited boron on the surface of the silicon substrate and diffused it into the silicon substrate.

[0003]

The conventional diffusion method has the following problems.

[0004] Deformation of the boron nitride plate is likely to occur due to densification due to heat and boron deposition. Therefore, the distance between the boron nitride plate and the silicon substrate differs depending on the location, and the amount of boron deposited on the silicon substrate also changes, resulting in a variation in the diffusion concentration. Also, when the oxidation process of the boron nitride plate and the deposition process of boron are repeated, the oxidation proceeds unevenly not only on the surface of the boron nitride plate but also on the inside due to the porosity of the boron nitride itself, resulting in diffusion of boron. Since the concentration varies, it is impossible to use the boron nitride plate efficiently to the end.

An object of the present invention is to solve the above-mentioned problems and to provide a reproducible boron nitride plate having a uniform boron diffusion concentration without deformation of the boron nitride plate.

[0006]

According to the present invention, in order to achieve the above object, boron nitride is deposited on the surface of a core having a melting point higher than that of a furnace tube used for diffusion by means such as sputtering. It is intended to be.

[0007]

1 and 2 show an embodiment of the present invention, and FIG. 1 is a sectional view of a boron nitride plate of the present invention. FIG. 2 shows a sectional view of the core tube. In both figures, 1 is a substance having a higher melting point than the furnace tube, such as sapphire, 2 is boron nitride, 3 is a plate, 4 is a boron oxide layer, 5 is a silicon substrate, 6 is a quartz boat, 7 is a furnace tube. is there. The present invention uses a boron nitride plate 3 in which boron nitride (BN) 2 is deposited on a substance 1 having a higher melting point than a furnace tube 7 by sputtering as shown in FIG. As shown in FIG. 2, the silicon substrate 5 is placed in parallel on the quartz boat 6 with the plate 3 having the surface oxidized by the oxidation step shown in FIG. Boron is diffused into the silicon substrate. As a result, there is no deformation of the plate compared to the conventional diffusion of boron nitride only,
Diffusion corresponding to long-time heating at a high temperature can be carried out, and variations in boron diffusion concentration can be eliminated. Boron nitride can be deposited again by means of sputtering or the like and recycled. Here, when the melting point of the furnace tube 7 is 1500 ° C., the substance 1 having a high melting point is an oxidation-resistant substance, such as sapphire (melting point: about 2000 ° C.). This is because high temperature heating (800 to 1) during boron deposition and diffusion is performed.
(000 ° C.), as a matter of course, no deformation occurs, and the strength of the plate can be sufficiently ensured integrally with the surrounding boron nitride.

[0008]

According to the present invention, according to the present invention, boron nitride (B
Since N) is deposited, the melting point of the plate is higher than that of a plate containing only boron nitride (BN), so that heat can be diffused at a high temperature and, at the same time, the strength of the plate can be improved and deformation hardly occurs. Variation in boron diffusion concentration can be reduced. Further, when the boron nitride (BN) oxidation and deposition steps are repeated and the surface boron nitride (BN) is reduced, boron nitride (BN) is deposited on the plate again by means such as sputtering. Can be played.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing one embodiment of the present invention.

FIG. 3 is a sectional view of a conventional example.

[Explanation of symbols]

1: a substance having a higher melting point than the furnace tube, 2: boron nitride (B
N), 3: plate, 4: boron oxide layer, 5: silicon substrate, 6: quartz boat, 7: core tube.

Claims (3)

[Claims] 1. In boron diffusion for diffusing boron into a silicon substrate, boron nitride is deposited on the surface of a core having a melting point higher than that of a furnace tube used for diffusion by a deposition means such as sputtering. A plate for boron diffusion characterized by the following. 2. The plate according to claim 1, wherein the core of the boron diffusion plate according to claim 1 is formed of an oxidation-resistant substance. 3. The boron diffusion plate according to claim 1, wherein the core of the boron diffusion plate is sapphire.