JPH04337630A - Furnace for heat-processing semiconductor wafer - Google Patents

Abstract

PURPOSE:To reduce variation across the semiconductor wafer surface during thermal processing by reducing the non-uniform gas flow caused by discharging gas in the oxidation, diffusion, and other thermal processes applied to the semiconductor wafer. CONSTITUTION:A preliminary evacuation room is placed on the opening end side of a furnace pipe 5 in a thermal processing furnace. The room 1 and the furnace pipe opening sections form an exhaust gas structure which can change the opening area or the opening density in accordance with the distance from the exhaust pipe 16 and achieve uniform exhaust from the furnace pipe 5, and by attaching a pressure sensor 17 to the exhaust pipe 16 to monitor the exhaust strength inside the furnace pipe 5 during thermal processing and moving the semiconductor wafer 20 in and out of the furnace, a variable damper 10 on the lower side controls the exhaust strength.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to heat treatment of semiconductor wafers in the semiconductor manufacturing industry, and more particularly to a heat treatment furnace for semiconductor wafers used in oxidation and diffusion steps of semiconductor wafers.

0002

2. Description of the Related Art The operation of a conventional heat treatment furnace for semiconductor wafers 3 will be explained below with reference to the drawings. As shown in FIG. 4, the conventional heat treatment furnace for semiconductor wafers 3
Wafers (hereinafter referred to as wafers) 3 are loaded onto the boat 2 and inserted into and taken out from the furnace core tube 5. The temperature inside the furnace core tube 5 is controlled by closed loop control using a thermocouple installed near the heat treatment heater 6, and the output to the heat treatment heater 6 is controlled by zero-cross control or phase control. This is done by changing the flowing current.

[0003] The furnace core tube 5 in the heat treatment furnace is controlled by a gas supply device 4 to maintain an atmosphere according to the purpose of treatment. Normally, the inside of the furnace core tube 5 is controlled to have an inert gas atmosphere when the semiconductor wafer 3 is taken into and taken out of the furnace. After the wafers 3 and the boat 2 have been moved to a predetermined heat treatment position, the wafers 3 are heat treated. In order to improve the uniformity and controllability of heat treatment and to reduce thermal shock to wafer 3, the temperature when wafer 3 enters and exits the furnace is set lower than the wafer 3 heat treatment temperature, and wafer 3 is removed from outside the furnace. After reaching the heat treatment position, the temperature inside the furnace is raised, and after the heat treatment of the wafer 3 is completed, the temperature inside the furnace is lowered and the wafer 3 is taken out of the furnace. The atmosphere inside the furnace is controlled by the heat treatment heater 6 and the gas supply device 4, and the gas supplied into the furnace core tube 5 through the gas introduction tube 18 is passed through the exhaust pipe 16 attached near the open end of the furnace core tube 5. It is discharged from the furnace core tube 5. The exhaust pipe 16 is a single pipe and is installed perpendicularly to the longitudinal direction of the furnace core tube 5. Further, in the figure, 8 is a boat stand, 9 is a liner tube, 11 is a quartz buffer plate, 12 is a motor, 13 is a ball screw, and 14 is a guide.

0004

[Problems to be Solved by the Invention] In the conventional wafer heat treatment furnace described above, only one exhaust pipe is connected to the open end of the furnace core tube during the heat treatment of wafers within the furnace core tube. When the gas flow inside the core tube is on the open end side of the furnace core tube, steady drifting tends to occur, and the uniformity of heat treatment such as oxide film formation and impurity diffusion on the semiconductor wafer surface is affected at the open end side of the furnace core tube. The heat treatment uniformity in the center of the furnace core tube was poor. In addition, since constant exhaust is performed both during entering and exiting the furnace and during heat treatment, it is not possible to respond to changes in the amount of gas supplied or opening and closing of the furnace mouth. The drawback was that it created situations where it was too strong.

An object of the present invention is to provide a heat treatment furnace for semiconductor wafers that solves the above-mentioned problems.

[0006]

[Means for Solving the Problems] In order to achieve the above object, in the semiconductor wafer heat treatment furnace according to the present invention,
A heat treatment furnace that has a preliminary exhaust chamber and an opening, and performs heat treatment on semiconductor wafers in a furnace core tube, the preliminary exhaust chamber comprising:
The opening is provided along the outer periphery of the open end of the furnace core tube and connected to the exhaust pipe, and the opening is provided along the circumferential direction of the open end of the furnace core tube. The opening area or the opening density of the opening portion is changed depending on the distance of the opening position from the exhaust pipe.

[0007]

[Function] In the wafer heat treatment furnace of the present invention, an exhaust preliminary chamber connected to an exhaust pipe is provided on the outer periphery of the open end side of the furnace core tube for the wafer heat treatment furnace, and the exhaust is uniformly exhausted from the periphery of the furnace core tube. In order to achieve this, there are multiple openings between the furnace core tube and the exhaust preparatory chamber, and the opening area of the openings increases as the distance from the exhaust tube increases, so that exhaust can be uniformly exhausted from the furnace core tube. This is what I did.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG. 2(a)
2(a) is a sectional view showing the furnace core tube according to the present invention, and (b) is a sectional view showing the furnace core tube according to the present invention.
), and FIG. 3 is a block diagram of the device of this embodiment.

In the figure, the present embodiment includes a boat 2 on which semiconductor wafers 3 are loaded, a gas supply device 4 for controlling the atmosphere for heat treatment, a heat treatment heater 6 serving as a heating source for the semiconductor wafers, and a boat 2 for loading semiconductor wafers 3. A furnace core tube 5 where heat treatment is performed and a boat loading mechanism (boat stand 8, motor 12,
This is a semiconductor wafer heat treatment furnace having a ball screw 13 and a guide 14), and an exhaust preliminary chamber 1 connected to an exhaust pipe 16 is provided on the outer periphery of the open end side of the furnace core tube 5. There are a plurality of openings 1a, 1a... that communicate with the chamber 1, and the opening area (or opening density) of the openings 1a, 1a... is changed according to the distance from the exhaust pipe 16, and the area around the furnace core tube 5 is changed. The exhaust structure is such that the exhaust can be discharged more uniformly, and the exhaust pipe 16 is further equipped with a variable damper 10 and a pressure sensor 17. Further, 9 is a liner tube, 11 is a quartz buffer plate, and 18 is a gas introduction tube.

In the embodiment, the boat 2 loaded with wafers 3 is moved to the heat treatment position of the wafers 3 (normally, the longitudinal centers of the boat 2 and the heater 3 coincide with each other) by a boat loading mechanism based on the boat loader controller C2. position). Gas controller C1
, the inside of the furnace core tube 5 is controlled to a predetermined furnace entry/exit atmosphere by the gas supply device 4 during the furnace entry based on the heat treatment furnace controller C3. Based on the temperature controller C4, after completion of furnace charging, the inside of the furnace core tube 5 is replaced with a predetermined heat treatment atmosphere, and the wafer 3 is heat treated. After the prescribed heat treatment is completed,
The inside of the furnace core tube 5 is replaced with the furnace atmosphere by the gas supply device 4, and the wafer 3 is moved out of the furnace by the boat loading mechanism. The gas supplied into the apparatus from the gas supply device 4, except during inlet/output from the furnace, passes through the furnace core tube 5, the exhaust preparatory chamber 1, and is exhausted through the exhaust pipe 16. Exhaust controller C
5, when entering and exiting the furnace, the exhaust is strengthened in order to improve the gas replacement efficiency and reduce the entrainment of oxygen in the furnace, but during heat treatment, the pressure inside the furnace does not change rapidly. Control the exhaust intensity depending on the supplied gas flow rate. That is, the exhaust pressure is monitored by the pressure sensor 17, and the opening degree of the damper is adjusted by the variable damper 10 so as not to deviate greatly from the pressure set by the heat treatment furnace controller C3.

[0011]

As explained above, the present invention provides a furnace core tube for a heat treatment furnace for a wafer heat treatment furnace with an exhaust preliminary chamber connected to an exhaust pipe on the outer periphery of the open end side of the quartz tube. There are a plurality of openings between the exhaust pipe and the exhaust preliminary chamber, and the opening area or opening density changes as the distance from the exhaust pipe increases;
By controlling the intensity of the exhaust, it is possible to maintain a uniform and stable flow of gas on the opening side of the furnace core tube in a wafer heat treatment furnace, thereby preventing wafer oxidation, diffusion, etc. due to uneven gas flow. This has the effect of reducing in-plane variations in heat treatment.

[Brief explanation of drawings]

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

2(a) is a sectional view showing the furnace core tube in FIG. 1, and FIG. 2(b) is a sectional view taken along line A-A in FIG. 2(a).

FIG. 3 is a block diagram of the device of this embodiment.

FIG. 4 is a sectional view showing a conventional wafer heat treatment furnace.

[Explanation of symbols]

1　Exhaust preliminary chamber 2 Boat 3 Semiconductor wafer 4 Gas supply device 5 Furnace core tube 6 Heat treatment heater 8 Boat stand 9 Liner pipe 10 Variable damper 11 Quartz buffer plate 12 Motor 13 Ball screw 14 Guide 15 Soaking tube 16 Exhaust pipe 17 Pressure sensor 18 Gas introduction pipe

Claims (1)

[Claims] Claim 1: A heat treatment furnace for heat-treating semiconductor wafers in a furnace core tube, having a preliminary exhaust chamber and an opening, the preliminary exhaust chamber extending along the outer periphery of the opening end of the furnace core tube. The opening is provided along the circumferential direction of the open end side of the furnace core tube and connects the furnace core tube and the exhaust preliminary chamber. A heat treatment furnace for semiconductor wafers, wherein the opening area or density of the opening is changed depending on the distance of the opening position from the exhaust pipe.