JPS63110632A - Diffusion of impurity - Google Patents

Abstract

PURPOSE:To enable rugged substrate to be impurity-diffused by a method wherein substrates to be diffused opposing to silicon substrates with coating diffusion source sintered thereon are juxtaposed with one another while respective substrates are heated by an encircling heater up to specified temperature to diffuse impurity on the substrate to be diffused. CONSTITUTION:Silicon substrates 1 with coating diffusion source 2 sintered thereon as well as the other substrates 3 with deep grooves cut therein opposing to the substrates 1 are juxtaposed with one another on a quartz susceptor 4. The quartz susceptor 4 is provided with a quartz furnace core tube 6 encircled by a resistor heater 5 to be heated. The Si substrates 1 with coating diffusion source 2 containing As sintered thereon opposing to the silicon substrates 3 are inserted into the quartz furnace core tube 6. At this time, mixed gas of N2, O2 is fed from a gas leading-in port 7 to perform the diffusion process. Through these procedures, rugged sides and bottom part of rugged substrates to be diffused can be diffused evenly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application J] The present invention relates to an impurity diffusion method in a semiconductor device manufacturing method.

[Conventional technology]

Conventionally, this type of impurity diffusion method includes a gas diffusion method, a solid source diffusion method, a coating diffusion method, and an ion implantation method.

[Problem that the invention attempts to solve] -E Each of the conventional methods described above has the following drawbacks.

i) Regarding gas diffusion methods, open tube diffusion methods using toxic substances such as arsenic are harmful to the body and are impractical; Oxide leaks out each time the high-temperature round pipe is opened and closed, creating a safety and hygiene problem.

ii) Solid source diffusion method is aluminum oxide.

Since diffusion impurities (for example, 13□03, etc.) are mixed into oxides such as acid 1 and sium, when diffusion impurities are diffused into silicon/(Si) substrates, impurities such as aluminum and magnesium are also diffused at the same time. As a result, the crystallinity of the Si substrate deteriorates, and the electrical characteristics also deteriorate.

1ii) In the coating diffusion method, it is sufficient if the diffusion target substrate is completely flat, but if the diffusion target substrate has irregularities, the concentration and depth of the diffusion impurity will be non-uniform due to differences in coating film thickness and stress. In particular, if there are deep grooves or the like in the substrate to be diffused, a very large impurity concentration depth unevenness will be observed at the sides and bottom of the vortex.

iv) In the ion implantation method, impurities cannot be introduced into the surface parallel to the ion implantation direction of the substrate to be diffused.
Impurities cannot diffuse into the m-plane.

The purpose of the present invention is to eliminate these drawbacks, to safely diffuse harmful elements such as arsenic, to prevent deterioration of crystallinity and electrical properties, and to diffuse even if the substrate to be diffused has irregularities such as grooves. side,
An object of the present invention is to provide an impurity diffusion method that enables uniform impurity diffusion regardless of the bottom part.

1' Means for solving the problem j The structure of the impurity diffusion method of the present invention uses a sintered silicon substrate of a coating diffusion source as a diffusion source, and a coating is placed opposite to the coating diffusion limited sintered silicon substrate. The method is characterized in that diffusion substrates are installed, each of these substrates is heated from the surroundings to a predetermined temperature, and the impurity is diffused into the partial diffusion substrate 1 using the diffusion source as an impurity.

(1 example) Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a longitudinal cross-sectional view of a manufacturing apparatus illustrating an embodiment of the present invention. A silicon substrate 1 sintered on the surface of the coating diffusion source 23 is mounted on a quartz support 4 together with a diffusion target substrate 3 having a deep vortex so as to face the surface of the substrate 1 .

This quartz support stand 4 is provided inside the quartz furnace core tube 6,
The quartz furnace core tube 0 is surrounded by a resistance heating heater 5 and heated to a predetermined temperature. A constant atmosphere is maintained by introducing gas such as N2, 02, etc. from the gas introduction lower part of this quartz furnace core tube 6.

A coating diffusion source 2 containing As is placed in the quartz furnace core tube 6 at a rate of 700 mm.
A Si substrate 1 sintered for 10 minutes in a N2 atmosphere at
This quartz furnace core tube 6 is resistance heated.
The temperature is maintained at 1140° C. by a heater 5. At this time, gas introduction [7 to N210e/min, 02100
A mixed gas of cc,/min was flowed to perform diffusion for 3 hours. side of a deep vortex.

A diffusion layer with a depth of 1.8 μm and a single layer resistance of 400Ω7/hole can be formed uniformly on the bottom. In addition, since the quartz support 11 is sufficiently cooled in an area without the resistance heating heater 5 before being taken out, the vaporized As oxide is present only in the quartz furnace core tube and does not leak outside, which poses a safety problem. There isn't.

In addition, a coating diffusion source 2 containing B was sintered at 500° C. using a coating diffusion source sintered silicon substrate 1, and a silicon substrate 1 on which B was diffused at 1000° C. for 20 minutes was removed using siltlue soching after SiO2 was removed. When I checked for crystal defects, the number of crystal defects was less than 500/r, 2. On the other hand, the solid source diffusion source of B (B203 A l! 2
03 M, 02 series>, the crystal defects were similarly checked on a Si substrate diffused with B, and the result was ~106 defects/c.
No. 12 had many crystal defects.

"Effects of the Invention" As explained above, the present invention uses a sintered silicon substrate as a coating diffusion source for diffusion, and places a substrate to be diffused to face the sintered silicon substrate for diffusion. This has the effect of safely diffusing harmful substances and uniformly diffusing them to the sides and bottom of the uneven diffusion target substrate without crystal defects.

[Brief explanation of the drawing]

No. 11a is a longitudinal sectional view of a manufacturing apparatus for explaining an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Coating diffusion source sintered silicon substrate, 2... Sintering coating diffusion source on the substrate surface, 3... Diffusion target substrate having deep grooves, 4... Quartz support base, 5... resistance heating heater,
6...Quartz furnace core tube, 7...Gas inlet. 1.1. of

Claims (1)

[Claims] A sintered silicon substrate of a coating diffusion source is used as a diffusion source, a substrate to be diffused is installed to face the sintered silicon substrate of the coating diffusion source, each of these substrates is heated from the surroundings to a predetermined temperature, and the diffusion source is heated to a predetermined temperature. An impurity diffusion method characterized in that the impurity is diffused onto the diffusion substrate as an impurity.