JPH02306619A - Impurity diffusing equipment - Google Patents

Abstract

PURPOSE:To discharge outwardly product and unreacted material which have not become diffusion source for semiconductor material without solidifying them in a furnace core tube, by heating the inside on the discharging side of the furnace core tube by a heater. CONSTITUTION:A heater 6 for heating the inside of a furnace core tube 1 on the lower part side of semiconductor 3 in the gas flow direction is installed, and the inside on the discharging side of the furnace core tube 1 is heated at a high temperature by the heater 6. Thereby, product P2O5 which has not become phosphorus diffusion source for a substrate 3 and unreacted phosphorus are discharged to the outside from a discharge vent 1b without being solidified in the furnace core tube 1. The product and the unreacted phosphorus do not attach and deposit on the inner wall of the furnace core tube 1 and the contact part between the main body of the furnace core tube 1 and a cap 2. Hence, when the substrates 3... after diffusion processing are taken out from the furnace core tube 1, the product and the unreacted phosphorus do not attach on the substrates 3 and a boat 4 for diffusion use, and it does not happen that the cap 3 can not be opened on account of attaching of the product or the unreacted phosphorus. Thereby the semiconductor substrates after diffusion processing can be taken out from the furnace core tube without damaging the uniformity of diffusion.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an impurity diffusion device used in a semiconductor manufacturing process, and more particularly to an impurity diffusion device for performing phosphorus diffusion on a semiconductor substrate.

<Prior art> An impurity diffusion device for diffusing phosphorus into a semiconductor substrate,
An example of a conventional configuration is shown in FIG.

A gas supply source (not shown) that supplies a mixed gas of Ox and N2 to the gas inlet 1a of the furnace core tube 1, and a POC 13
A tank 7 containing .

The exhaust side end of the furnace core tube 1 has a cap structure, and by opening the cap 2, the semiconductor substrates 3 to be subjected to phosphorus diffusion can be placed in the diffusion boat 4 and removed from the furnace. It can be placed at a predetermined position inside the core tube 1. Further, around the outer wall of the furnace core tube 1, a semiconductor substrate 3...
A heater 5 is disposed to maintain the temperature of the atmosphere around 3 at about 900°C.

In the above configuration, while a mixed gas of 02 and N2 is supplied into the furnace core tube 1 from the gas inlet 1a, POCl
When the valves 7a and 7b of the 3 tank 7 are opened, POC12 vapor flows into the furnace core tube 1 using N2 gas as a carrier, and p and o are generated by the reaction between the POC1i steam and the 02 gas inside the furnace core tube 1. be done. This product P20. By exposing the surface of each semiconductor substrate 3 to the flow, phosphorus is diffused into the substrate 3. Note that the semiconductor substrates 3 . . . 3 that have been subjected to predetermined phosphorus diffusion are taken out to the outside together with the diffusion board 4 by opening the cap 2 .

<Problem to be solved by the invention> By the way, according to the impurity diffusion device shown in FIG.
The internal temperature on the exhaust side is as low as 100 to 200°C.
Therefore, the product P that could not become a diffusion source to the substrate 3
20. Otherwise, unreacted phosphorus solidifies and adheres to the inner wall of the furnace core tube 1 on the exhaust side and the contact area between the furnace core tube 1 body and the cap 2. The amount of this deposit increases as the phosphorus diffusion process is repeated (and if it is left as it is, when the semiconductor substrates 3...3 are removed,
There was a problem in that products and unreacted phosphorus adhered to the reactor, resulting in poor diffusion uniformity, and furthermore, there was a problem in that the cap 2 was stuck to the main body of the furnace core tube 1, making it impossible to open the cap 2.

Means for Solving the Problems> The present invention has been made to solve the above problems.
The structure will be explained with reference to FIG. 1 corresponding to an embodiment. The present invention provides a method for disposing a semiconductor material in a furnace core tube 1 by flowing a gas containing a diffusion source inside the furnace core tube 1. 3... In the device for diffusing impurities into 3, the furnace core tube 1
It is characterized in that a heater 6 is provided for heating the inside of the semiconductor material 3 on the downstream side in the gas flow direction.

Effect: By heating the inside of the exhaust side of the furnace core tube 1 with the heater 6, the product P20. which could not become a diffusion source to the semiconductor material 3 is removed. The unreacted phosphorus is not solidified in the furnace core tube 1 (it is exhausted to the outside).

<Example> FIG. 1 is a configuration diagram of an embodiment of the present invention.

The furnace core tube 1 is provided with a gas inlet 1a and an exhaust port 1b. The gas inlet 1a includes a gas supply source (not shown) that supplies a mixed gas of o2 and N2, and a POC.
A tank 7 containing 13 is connected. Note that the tank 7 is connected to the POC 1 and a replenishment pipe 7c, and the poc 1! The liquid level can always be kept constant.

The exhaust side end of the furnace core tube 1 has a cap structure, and by opening the cap 2, the semiconductor substrates 3 to be subjected to phosphorus diffusion are mounted on the diffusion boat 4. It can be placed at a predetermined position inside the furnace core tube 1. Further, a substrate heater 5 is disposed around the outer wall of the furnace core tube 1, and the temperature of the atmosphere around the substrates 3 can be maintained at about 900°C.

The above structure is similar to the conventional device shown in FIG. 2, and phosphorus diffusion into the substrate 3 is also carried out according to the same procedure as in the conventional device.

Now, a substrate heater 5 is installed around the outer wall of the exhaust side of the furnace core tube 1.
An exhaust side heater 6 is provided that extends from near the end to the contact area between the furnace core tube 1 body and the cap 2. The exhaust side heater 6 and the substrate heater 5 are each controlled individually, and the exhaust side heater 6 can heat the temperature inside the furnace core tube 1 on the exhaust side to about 500 to 600°C.

According to this embodiment, by heating the inside of the exhaust side of the furnace core tube 1 to a high temperature with the heater 6, the products P, O1 and unreacted phosphorus that could not become a source of phosphorus diffusion to the substrate 3 are removed.
It is exhausted to the outside from the exhaust port 1b without solidifying in the furnace core tube 1, and products and unreacted phosphorus adhere to and accumulate on the inner wall of the furnace core tube 1 and the contact area between the furnace core tube 1 body and the cap 2. There's nothing to do. Therefore, the substrate 3 after the diffusion treatment...
3 to the outside from the furnace core tube 1, products and unreacted phosphorus do not adhere to the substrate 3 and diffusion boat 4, and the cap 2 is free from adhering products and unreacted phosphorus. It does not become impossible to open.

<Effects of the Invention> According to the present invention, since a heater is provided for heating the inside of the exhaust side of the furnace core tube, when performing phosphorus diffusion, for example, the inner wall of the furnace core tube, the furnace core tube body, and the cap are heated. It is possible to prevent phosphorus diffusion sources and unreacted phosphorus from adhering to the contact area. Thereby, the semiconductor substrate after the diffusion treatment can be taken out from the furnace core tube without impairing the uniformity of diffusion, and the yield is improved. Furthermore, the cap is not stuck to the furnace core tube body due to deposits such as phosphorus diffusion sources, and it is possible to prevent the camp from becoming impossible to open.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention, and FIG. 2 is a diagram showing an example configuration of a conventional impurity diffusion device. 1 Furnace core tube 1a Inflow port 1b Exhaust port 2 Camp 3 Semiconductor substrate 4 Diffusion boat 5 Substrate heater 6 Exhaust side Heater 7...tank (POCl2) Patent applicant: Sharp Corporation Agent: Patent attorney Nishi 1) New Figure 1 Figure 2

Claims (1)

[Claims] In an apparatus for diffusing impurities into a semiconductor material placed in a furnace core tube by flowing a gas containing a diffusion source inside the furnace core tube, a downstream side of the semiconductor material in the gas flow direction of the furnace core tube is provided. An impurity diffusion device characterized by being equipped with a heater for heating the inside.