JPS60122799A - Heat treatment of semiconductor wafer - Google Patents

Abstract

PURPOSE:To stabilize the temp. distribution in a treating chamber and to perform a wafer treatment having excellent quality and reliability by introducing O2 and H2 combined in the outside part into a reaction tube and subjecting a semiconductor wafer to a heat treatment in a wet oxygen atmosphere. CONSTITUTION:H2 is ejected from the nozzle 18 of a hydrogen supply pipe 14 of which the part near the nozzle is heated by a spiral heater 16 into the innermost layer box 11 of a hermetic vessel 8 housed in a doping box 9 and at the same time, O2 is supplied from an oxygen supply pipe 18 into said box to burn and combine 20 H2 and O2, thereby yielding wet oxygen. The wet oxygen is introduced from the box 11 via a conduit 19 and an auxiliary conduit 28 wound with a ribbon heater 30 to a reaction tube 26 having a heater part 31 so that a semiconductor wafer is heat-treated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a technique for performing oxidation treatment or diffusion treatment in a wet oxygen atmosphere.

For example, regarding heat treatment technology, Electronic
Integrated C1rcuits (J, A
11ison), pages 48 to 50.

In the oxidation/diffusion process of semiconductor thin plates (wafers) used in the production of semiconductor devices, hydrogen (
H2), a wet oxygen generation method (growning method) by direct reaction of oxygen (0,) is generally employed. As a method of producing wet oxygen of this type, a hydrogen combustion mechanism for hydrogen gas as shown in FIG. 1 is known. That is, a hydrogen supply pipe 3 made of quartz glass is inserted in an airtight state into a thin tail pipe 2 of a process tube 1 made of quartz glass in a furnace through the mutual rubbing surfaces. Hydrogen (H2) is supplied. Also 1
A branch pipe 4 is made at the closed end of the core tube 1 in parallel with the tail pipe 2, and oxygen (02) is supplied into the core tube 1 through this branch pipe 4.

Further, a heater section 5 consisting of a soaking tube, a heater, etc. is disposed around the outer periphery of the furnace core tube 1, and heats a processing chamber 6 within the furnace core tube 1 to an appropriate temperature. When forming an oxide film on the wafer, the silicon wafer is placed into the processing chamber 6 heated to a predetermined temperature using a heat treatment jig or the like (not shown).
Thereafter, oxygen is supplied into the processing chamber 6 from the branch pipe 4, and hydrogen is also introduced into the processing chamber 6 through the hydrogen supply pipe 3. Since the inside of the processing chamber 6 has reached a predetermined temperature and hydrogen and oxygen are each sent into the processing chamber 6 at a predetermined ratio,
Hydrogen and oxygen burn without exploding (flame 7 in the figure) and turn into water vapor (indicated by a dot in the figure). Oxygen containing water vapor, that is, wet oxygen, is supplied toward the center of the reactor core tube 1, and A thermal oxidation (St, .) film is formed on the surface.

However, such a mechanism has the following drawbacks.

(1) The temperature of an elongated reactor core tube is generally controlled by three heaters A, B, and C arranged in series, and as shown in FIG. 2, the temperature distribution is constant in the central part.

In addition, in order to maintain a constant temperature distribution over a constant length, heaters A9C located at both ends of the
The temperature at both ends of the core tube is controlled to be slightly higher than that at the center. However, when hydrogen and oxygen are reacted and burned at the closed end of the core tube, the temperature rises partially at the back of the core tube, as shown by the two-dot chain line in Figure 2, and the temperature distribution inside the core tube is uniform. is damaged, and the formation of the oxide film becomes non-uniform.

Note that, in general, the central heater B only plays the role of raising and lowering a constant temperature, and does not have the function of correcting the temperature difference between the two ends of the reactor core tube.

(2) It is necessary to check the ignition (combustion) state in order to confirm safety and whether oxide film is being formed properly, but combustion takes place inside the core tube, and the outside of the core tube is heated. 5 ignition (flame 7) because it is surrounded by
) must be seen through the opening in the core tube. However, this is because the wafers are inserted into the reactor core tube in a row.

The problem is that it is difficult to confirm ignition (combustion).

(3) If an explosion occurs due to a change in the mixture ratio of hydrogen and oxygen or the temperature in the processing chamber becomes low, the reactor core tube is made of quartz glass, so it will break into powder and scatter into the surrounding area, creating a dangerous situation. In addition, it has the disadvantage of damaging the wafer and heater section.

(4) Particularly in the case of a diffusion furnace, it is common to provide a new branch pipe in addition to the tail pipe on the closed end side of the reactor core tube in order to supply the reactant gas. However, in the above-described structure, the structure of the reactor core tube becomes complicated.

Manufacturing costs increase. Furthermore, since there are two thin and easily broken tail pipes and two branch pipes at one end of the furnace core tube, handling is more troublesome than the conventional furnace core tube that only has a tail pipe.

Therefore, an object of the present invention is to provide a heat treatment technique in wet oxygen that does not disturb the temperature distribution within the processing chamber.

Another object of the present invention is to provide a device that allows one ignition state to be easily confirmed and is highly safe.

In order to achieve such an object, the present invention provides a heat treatment method that can eliminate adverse effects on wafers and the like by burning oxygen and hydrogen outside one reaction tube.

FIG. 3 is a schematic diagram showing a wet oxygen generation device and a diffusion furnace including the wet oxygen generation device used in an embodiment of the present invention. The figure shows an airtight container (box) 8 made of quartz glass. This container 8 is housed in a doping box 9 of a diffusion furnace.

Further, the container 8 has a three-layer structure, and the innermost layer box 10 is made of quartz glass so that it can withstand high temperatures and is free from impurities. Further, the outermost box 11 is made of a metal container, such as stainless steel, which has a strength that will not cause damage even if an explosion occurs inside the container. Also.

A heat insulating material such as quartz wool is inserted between the outermost box 11 and the innermost box 10 to enhance the heat insulation effect, forming a heat insulating layer 12.

A plurality of vibrators 13 are integrally attached to the innermost box 10 on its upper surface and side portions. That is, on the − side wall are a hydrogen supply pipe 14 for introducing hydrogen gas into the container 8 and an oxygen supply pipe 1 for introducing oxygen gas into the container 8.
5 is provided.

The hydrogen supply pipe 14 extends into the container through the innermost box 10, and its tip protrudes below the center of the ceiling of the innermost box 10. In addition, the hydrogen supply pipe 14 inside the container 8
A helical heater 16 is wound around the portion, and the innermost box 10° and the heat insulation layer 12 are connected to each other at both ends. Outermost box 1
The heater 16 extends outside the container through the heater 16 and is connected to a predetermined power source (not shown).The heater 16 is covered with quartz glass on the outside, and is connected to the innermost box 10 through the quartz glass. The upper part of the spiral part 17 of the heater 16 extends over the extension of the nozzle part 18 at the tip of the hydrogen supply pipe 14, and the upper part of the spiral part 17 of the heater 16 extends over the nozzle part 18 at the tip of the hydrogen supply pipe 14. It is designed to heat up.

Also, the innermost box 10 facing the nozzle part 18
A ceiling button is provided with a conduit 19 that directs water vapor (indicated by scattered dots in the figure) generated by the combustion reaction between the hydrogen gas spouted from the nozzle part 18 and the oxygen gas filling the container to the outside of the container 8. It is designed to lead together with oxygen. Additionally, a thermocouple terminal 21 is used to detect the temperature of the flame 20 due to combustion pressure.
has entered the vicinity of the flame 20 from outside the container. This thermocouple terminal 21 is covered with a storage tube 22 made of quartz glass that also extends to the innermost box 10 whose inner end is closed.

Further, a drain pipe 23 made of quartz glass is attached to the lower side of the container 8 to drain water accumulated at the bottom of the container. This drain pipe 23 has a drain cock 24.
is provided.

Although not shown, the container 8 is provided with a reaction gas supply pipe for processing the object to be processed. Further, the outermost box 11 and the heat insulating layer 12 are partially removed to form an observation window 25 so that the flame 20 burning inside the container 8 can be observed from outside the container. Note that a transparent protective plate with excellent heat resistance may be attached to the observation window 25 to serve as a protective plate when the innermost box 10 explodes. moreover,
Said innermost box 10. The heat insulating layer 12 has a structure that can be removed sequentially from the outermost layer box 11.

On the other hand, the conduit 19 protruding from the container 8 is a standard type reactor core tube 2.
It is connected to the narrow tail tube 27 of No. 6 through an auxiliary conduit 28 made of a tube made of fluororesin or the like. In addition, the connection part is equipped with a connector 2 that connects this generally known buried 1\0 Eve.
9 are used respectively.

Furthermore, a ribbon heater 30 is wrapped around the outer periphery of the connector 29 and the auxiliary conduit 28 to prevent the water vapor flowing inside the auxiliary conduit 28 from turning into water droplets, and to constantly supply wet oxygen at a constant temperature to the reactor core tube. There is. Further, numeral 31 in the figure is a heater section that heats the furnace core tube 26.

Next, the operation of supplying wet oxygen to the furnace core tube 26 will be explained. The vicinity of the nozzle portion 18 of the hydrogen supply pipe 14 is heated to a predetermined temperature by the heater 16, and oxygen gas is injected from the oxygen supply pipe 15 inside the container 8 to fill it with oxygen. Further, hydrogen gas is injected from the nozzle portion 18. Note that the hydrogen gas and oxygen gas are supplied in a predetermined ratio. As a result, the hydrogen injected from the nozzle portion 18 reacts with oxygen and burns, generating water vapor. Since the pressure inside the container 8 is high, the water vapor and oxygen (and reactant gases such as diffusion impurities, if necessary) in the container are transferred to the conduit 19. It is sequentially fed into the core tube 26 through an auxiliary conduit 28.

According to such an embodiment, the following effects are achieved.

(1) Wet oxygen supplied to the reactor core tube is always maintained at a constant temperature by a ribbon heater and is supplied to the reactor core tube. Therefore, the temperature distribution in the furnace core tube is stabilized, so that wafer processing with excellent quality and reliability can be performed, and the yield rate can also be improved.

(2) Since the combustion state can be easily observed through the observation window of the vessel, it can be confirmed whether or not steam is not being sent to the reactor core tube. Therefore, it is also possible to avoid carrying out Ueno treatment in a state where steam is not being applied.

(3) Even if an explosion occurs inside the container, the outermost box of the container is pressure resistant and strong, so quartz glass fragments will not scatter outside the container as in the case of conventional methods. Therefore, it is safe. Furthermore, unlike the conventional method, the wafer is not damaged by flying quartz glass pieces, so there is no reduction in yield. Furthermore, since the heater part is not destroyed by flying quartz glass pieces, the life of each part of the heat treatment furnace apparatus is extended, which also leads to a reduction in product processing costs.

(4) Since standard products such as tail pipes can be used for the reactor core tube, equipment costs are also reduced.

[Brief explanation of the drawing]

Figure 1 is a partial sectional view showing a wet oxygen generation mechanism that supplies wet oxygen to the core tube of a conventional diffusion furnace, Figure 2 is a temperature curve diagram showing the temperature distribution in the core tube, and Figure 3 is a diagram showing the present invention. 1 is a cross-sectional view showing a wet oxygen generation device and a diffusion furnace including the same. 1... Furnace core tube, 3... Hydrogen supply pipe, 5... Heater section. 6... Processing chamber, 7... Flame, 8... Container, 10...
・Innermost box% 11...Outermost box, 12
...insulation layer. 14... Hydrogen supply pipe, 15... Oxygen supply pipe, 16.
... Heater, 18 ... Nozzle part, 19 ... Conduit, 2
0... Flame, 21... Thermocouple terminal, 25... Observation window, 26... Furnace tube, 27... Tail tube, 28... Auxiliary conduit, 30... Ribbon heater, 31 ...Heater section. ,/- Agent Patent Attorney Akio Takahashi (;＼-9

Claims (1)

[Claims] 1. A method for heat treating semiconductor sea urchin, which is characterized in that when heat treating semiconductor sea urchin in a wet oxygen atmosphere, oxygen and hydrogen are combined outside the reaction tube and then introduced into the reaction tube.