JPH02201920A - Heat treatment furnace for semiconductor substrate - Google Patents

Abstract

PURPOSE:To prevent generation of a drift of reactant gas and eliminate ununiformity of partial pressure of the reactant gas by providing a reaction chamber, having a heater in the outer peripheral part thereof, at one end of a process-tube of a heat treating furnace, and directing an introduction nozzle, for introducing source gas into the reaction chamber, to the end wall of the reaction chamber. CONSTITUTION:A reaction chamber 9, having a heater 10 in the outer peripheral part thereof, is continuously provided at one end of a process-tube 1, and source gas is introduced into a reaction chamber 9 from introduction nozzles 11a, 11b directed to the end wall 9b of the reaction chamber 9. As a result, a drift of reactant gas is never generated near the introduction nozzles 11a, 11b, and the reactant gas flows in the process-tube 1 with nearly uniform pressure distribution from the reaction chamber 9, and a uniform diffusion layer can be formed in the surface layer of a semiconductor substrate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a heat treatment furnace for forming a P diffusion layer on the surface layer of a semiconductor substrate mainly using PHi gas.

(Prior Art) Conventionally, a heat treatment furnace for forming a P diffusion layer on a semiconductor substrate using a gas source such as PH3 gas has been configured as shown in the first diagram. The substrate C is heated by a heater d provided on the outer periphery of the process tube a, and a source gas, for example, a mixture of PH3, K, and 02 gases, introduced onto the surface from the introduction nozzle e reacts. P generated by
205 component is adhered and permeated to form a P diffusion layer on the surface layer of the substrate C. In this case, the nozzle e has PH3
One branch pipe f for introducing N2 gas and another branch pipe g for introducing 02 gas are connected, and the gases introduced from an external gas source through each branch pipe f and g are merged. The liquid is ejected from the nozzle e into the buselos tube a. j is an exhaust pipe connected to a vacuum pump.

(Problems to be Solved by the Invention) When the source gas is ejected from the nozzle e pointing inward in the process tube a as described above, a reaction gas pool area is formed at the root of the nozzle e, and the nozzle The partial pressure in the process tube a of the reaction gas blown out from e is high at the bottom near the nozzle e, increases upward as it moves away from the nozzle e, and the partial pressure of the reaction gas is high in the range shown by region i. In such a region hS
If f is formed, there is a drawback that it becomes difficult to control the resistance value distribution of the diffusion layer formed in the semiconductor substrate C.

Furthermore, when the semiconductor substrate C is placed on the paddle b and housed in the process tube a, the flow of the reaction gas in the tube a is divided into two by the paddle b as shown in the second diagram, and a uniform flow of the reaction gas is not achieved. I can't do it.

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat treatment furnace suitable for forming a diffusion layer with a good resistance distribution on a semiconductor substrate by eliminating reaction gas pools and uneven pressure within a process tube. It is.

(Means for Solving the Problems) In the present invention, a semiconductor substrate housed in a process tube is heated by a heater provided on the outer periphery of the process tube, while components of a gas source introduced into the process tube are In a device designed to diffuse and penetrate into the surface layer of a semiconductor substrate, a reaction chamber equipped with a heater on the outer periphery is connected to one end of the process tube, and an ejection port is provided in the reaction chamber toward the end wall. The above-mentioned problem is solved by providing an introduction nozzle for the source gas having the following characteristics.

(Function) A semiconductor substrate is placed in a process tube, and while the substrate is heated by a heater on the outer periphery, a source gas is introduced from an introduction nozzle, and components of the reaction gas generated by the reaction of the source gas are transferred to the surface layer of the substrate. Forming a diffusion layer by diffusing and permeating the process tube is similar to the conventional method, but a reaction chamber equipped with a heater on the outer periphery is connected to one end of the process tube, and the source gas flows through the end wall of the reaction chamber. Since the reaction gas is introduced into the reaction chamber from the introduction nozzle facing the direction of the reaction, there is no formation of a pool of reaction gas near the introduction nozzle, and the reaction gas flows from the reaction chamber through the process tube with an almost uniform pressure distribution. ,
A uniform diffusion layer can be formed on the surface layer of a semiconductor substrate, and heat treatment with good resistance value distribution can be performed.

(Embodiment) An embodiment of the present invention will be explained based on FIG. 3 of the drawing. In the figure, reference numeral (1) is a horizontally long cylindrical process tube made of quartz, and 2) is the tube (1). A plurality of semiconductor substrates made of Si are shown carried into the interior through an automatic door (3) provided at the end, and the semiconductor substrates (2) have passage holes (4 ) with a boat (5
) are placed upright with a distance between them and are moved into and out of said tube (1) by suitable transporter means. (6) is provided around the outer periphery of the tube (1), for example.
A heater having a uniform heating length of 000 mm, (7) an exhaust pipe, and (8) an auto door (3) of the tube (1).
A scavenger that covers the side edges.

At the end of the process tube (1) opposite to the auto door (3) side, there is a cylindrical part (9a) having approximately the same diameter as the tube (1).
) and one end is closed with an end wall (9b). A heater (IO) is provided surrounding the outer periphery of the reaction chamber (9). Two introduction nozzles (11
a) (11b) was provided. Source gases such as Pt1i gas and N2 gas are introduced into the reaction chamber (9) from one introduction nozzle (11a), and the other introduction nozzle (11a)
For example, a source gas of 02 gas is supplied from the reaction chamber (9
), but one introduction nozzle (11a) is extended into the reaction chamber (9), and the jet nozzle at its tip is inserted into the end wall (
9b), and in the example shown, the introduction nozzle (l
la) at the other introduction nozzle of the end wall (9b) <11
b).

The interior of the reaction chamber (9) communicates with the inside of the process tube (1), and one or more perforated plates (2) are interposed in the communication section, and nozzles (11a) (11b) are inserted into the reaction chamber (9). ) The residence time of the gas introduced from the tube (1) was increased to allow sufficient reaction to occur, and the gas flow rate within the tube (1) was made uniform to obtain a more uniform gas partial pressure.

To explain the operation of the embodiment shown in the third figure, the semiconductor substrate (2) placed on the boat (5) is placed in the process tube (1) by opening the auto door (3), and the heater (6) (1) is placed inside the process tube (1).
At the same time, PH, gas, N2 gas and O2 gas are introduced from the introduction nozzles (11a) and (11b) while exhausting from the exhaust pipe (7). Introduction nozzle (11a)
The source gas from <11b) remains in the reaction chamber (9) and generates a P2O5 reaction gas by heating the heater (IG). The gas ejected from (11a) flows from the end wall (9b) of the reaction chamber (9) along the peripheral wall of the tube (1), and the gas partial pressure of P2O5 in the tube (1) can be adjusted. There is no occurrence of a pool of reactive gas at the base of the nozzle (11a).

Further, since the flow rate of the reaction gas flowing from the reaction chamber (9) into the tube (1) is made uniform by the perforated plate (2), the partial pressure of the reaction gas can be made even more uniform.

The P2O5 reaction gas adheres to the surface of the substrate (2) inside the tube (1), and a diffusion layer is formed by the P component diffusing and penetrating into the inside of the substrate (1), but the partial pressure of the reaction gas is uniform. By doing so, the resistance value distribution of the diffusion layer can also be made uniform.

By forming gas passage holes (4) at the top and bottom of the boat (5) on which the substrate (2) is placed, the flow of the reaction gas within the tube (1) is not divided.

(Effects of the Invention) As described above, according to the present invention, a reaction chamber equipped with a heater on the outer periphery is provided at one end of a process tube of a heat treatment furnace, and an injection port of an introduction nozzle for introducing source gas into the reaction chamber is provided. By directing the reaction gas toward the end wall of the reaction chamber, it is possible to prevent the formation of a pool of reaction gas, and also to allow the reaction gas to flow along the circumferential surface of the process tube, eliminating unevenness in the partial pressure of the reaction gas. This has effects such as making it possible to make the resistance value distribution of the diffusion layer of the substrate uniform.

[Brief explanation of the drawing]

Figure 1 is a cut side view of the conventional example, Figure 2 is the ■-■ of Figure 1.
3 is a cutaway side view of an embodiment of the present invention, and FIG. 4 is a sectional view taken along line IV--IV in FIG. 3. (1)...Process tube (2)...Semiconductor substrate (6) (10...Heater (
9)...Reaction chamber (9b)...End wall (1
1a) (11b) =-Introduction nozzle (ID...
Perforated plate figure 3

Claims (1)

[Claims] 1. A semiconductor substrate housed in a process tube is heated by a heater provided on the outer periphery of the process tube, while components of a gas source introduced into the process tube are applied to the surface layer of the semiconductor substrate. In a device configured to diffuse and permeate, a reaction chamber equipped with a heater on the outer periphery is connected to one end of the process tube, and a source gas is introduced into the reaction chamber with a jet port directed toward the end wall of the reaction chamber. A heat treatment furnace for semiconductor substrates characterized by being equipped with a nozzle. 2. The heat treatment furnace for semiconductor substrates according to claim 1, characterized in that one or more perforated plates are interposed in the communication portion extending from the reaction chamber to the process tube.