KR0133677B1 - Heat traeting apparatus - Google Patents

Abstract

None.

Description

Heat treatment equipment

1 is an explanatory diagram showing a configuration of a conventional heat treatment apparatus.

2 is an explanatory diagram showing a pressure gradient in a gas introduction pipe in a conventional heat treatment apparatus.

3 is an explanatory diagram showing a configuration of a heat treatment apparatus of an embodiment of the present invention.

4 is a cross-sectional view showing the configuration of the gas introduction pipe of the present invention.

5 is a cross-sectional view showing another example of the gas introduction pipe of the present invention.

6 is a cross-sectional view taken along line III-III of the gas introduction pipe shown in FIG.

7 is an explanatory diagram showing the positional relationship between the gas introduction pipe and the suction exhaust hole formed in the inner reaction tube of the present invention.

(a) shows that the gas suction exhaust hole is formed in a form misaligned with the half surface of the inner reaction tube facing the gas introduction tube,

(b) shows that the gas suction exhaust hole was formed in the form shifted over the whole surface of the inner reaction tube 13,

(c) shows that the slitting gas suction exhaust hole is formed in the half surface of the inner reaction tube,

(d) shows that the slitting gas suction exhaust hole is formed on the entire surface of the inner reaction tube,

(e) is a figure which shows the gas suction exhaust hole formed in the open angle (theta) of an inner reaction tube.

* Explanation of symbols for main parts of the drawings

1: Base 2: Quartz tube

3: gas introduction pipe 4: gas ejection hole

5: quartz boat 6: semiconductor wafer

7: heater coil 8: gas discharge pipe

9: motor 10: pressure gradient

11: outer reaction tube 12: resistive heater

13: inner reaction tube 14: base

15 manifold 16 cover body

17: thermos 18: wafer boat

19: motor 20: rotation axis

21, 21 ': gas introduction pipe

21a, 21b, 21c, 21d, 21e, 21'a, 21'b, 21'c, 21'd, 21'e: gas ejection hole

22: gas suction exhaust hole 23: exhaust nozzle

24,25,26,27,28: sealing member 29: sealing means

W: Wafer

The present invention relates to a heat treatment apparatus used for diffusion treatment, chemical vapor deposition (CVD) treatment, oxidation treatment, and the like.

Conventionally, in order to form a thin film by vapor phase growth on the surface of a semiconductor wafer, the vertical heat treatment apparatus as shown in FIG. 1 is used.

In FIG. 1, reference numeral 1 denotes a base, and a bell jar made of a quartz tube 2 is vertically disposed on the base 1. Inside the quartz tube 2, a gas introduction pipe 3 for introducing a raw material gas is fitted to the base 1 and installed.

The gas introduction pipe 3 is provided with a plurality of gas ejection holes 4 at regular intervals along the axial direction, and the quartz boat 5 is housed inside the quartz tube 2. A plurality of semiconductor wafers 6 are mounted on the quartz boat 5 at predetermined intervals along the vertical direction.

The quartz boat 5 is rotated at a constant speed by the motor 9 in a state where the semiconductor wafer 6 is mounted thereon, and a heater coil 7 is wound around the outside of the quartz tube 2. . The heater coil 7 heats the semiconductor wafer 6 and the source gas to form a predetermined thin film on the surface of the semiconductor wafer 6.

The base 1 is provided with a gas discharge pipe 8 for discharging the gas after the reaction is completed.

However, such a heat treatment apparatus has the following drawbacks.

That is, in the gas introduction pipe 3, as shown in FIG. 2, the gas blowing holes 4 are formed at regular intervals along the axial direction. For this reason, the pressure gradient 10 in the gas introduction pipe 3 at the time of film formation shows a small value at the front end side of the gas introduction pipe 3, and a big value at the base side as shown in FIG. .

That is, as the ejection amount of the source gas decreases toward the front end of the gas introduction pipe 3, there is a drawback that a thin film having a uniform film thickness cannot be formed on the surface of the semiconductor wafer 6.

For this reason, the heat treatment apparatus requires that the film thickness of the thin film formed is uniform within the surface of the semiconductor wafer 6 and between each semiconductor wafer 6. Further, crystal defects due to thermal deformation, adhesion of dust, etc. to the semiconductor wafer 6 do not occur in the place where the thin film is formed, but are required for the heat treatment apparatus. The heat treatment apparatus is also required to have a large number of sheets of the semiconductor wafer 6 for each batch process.

In view of this, a heat treatment apparatus as disclosed in Japanese Patent Laid-Open No. 61-191015 or Japanese Patent Laid-Open No. 61-271818 is also developed.

However, these heat treatment apparatus suck and exhaust the reaction gas which passed between the semiconductor wafers 6 as the exhaust nozzle formed in the reaction tube. As a result, there is a problem that the diameter of the reaction tube becomes large, and reaction products and dust easily accumulate in the exhaust nozzle. Therefore, it is necessary to replace the exhaust nozzles regularly, and as a result, the operation rate of the apparatus is reduced.

In addition, a heat treatment apparatus in which a tube in which a graphite is uniformly applied to heat generated by high frequency induction heating or infrared heating in a reaction tube has the following drawbacks.

That is, when it is set to the high temperature pressure reduction state at the time of thin film formation, gas, such as oxygen, nitrogen, water, will generate | occur | produce in a reaction tube. The gas thus generated becomes impurities and enters into the semiconductor wafer by thermal diffusion, so that crystal defects are likely to occur in the semiconductor wafer.

An object of the present invention is to provide a heat treatment apparatus capable of producing a high quality thin film on the surface of a workpiece as a uniform film thickness and under high productivity.

In order to achieve the above object, the heat treatment apparatus of the present invention according to claim 1 mounts a plurality of objects to be processed on a boat at predetermined intervals in an inner reaction tube provided in an outer reaction tube, and surrounds the outer reaction tube. In the state where the object to be heated is heated by means of a heating means, the reaction gas is discharged in parallel with the surface of the object from a plurality of gas ejection holes formed in the pipe wall of the gas inlet tube inserted in the inner reaction tube in the longitudinal direction. A heat treatment apparatus for supplying and exhausting a plurality of exhaust holes formed in the tube wall of the inner reaction tube by an exhaust means at one end thereof through a gap between the inner reaction tube and the outer reaction tube, wherein the tube wall of the gas introduction tube is provided. The opening area of the gas ejection hole formed in the gas distribution may be constant along the longitudinal direction of the gas introduction pipe. The opening area of the exhaust hole formed in the tube wall of the inner reaction tube is set to increase gradually from the source side of the gas introduction tube toward the front end, and the exhaust gas is made to be uniform in the distribution of the gas exhaust amount along the longitudinal direction of the inner reaction tube. It is characterized in that it is set to gradually increase from one end of the means toward the other end.

The heat treatment apparatus of claim 2 is characterized in that the gas introduction pipe is made of quartz glass, and a protective film made of a SiC film is formed on the inner circumferential surface of the gas ejection hole formed in the pipe wall.

According to the heat treatment apparatus according to claim 1, the opening area of the gas ejection hole formed in the pipe wall of the gas introducing pipe is directed from the base of the gas introducing pipe to the front end so that the distribution of the gas ejection amount is constant along the longitudinal direction of the gas introducing pipe. While the opening area of the exhaust hole formed in the tube wall of the inner reaction tube is gradually increased, and gradually increases from one end to the other end of the exhaust means side so that the distribution of the gas exhaust amount is constant along the longitudinal direction of the inner reaction tube. Since it is set, it becomes possible to form the flow of reaction gas parallel and uniform to each surface of a several to-be-processed object, and to form a uniform high quality thin film on the surface of a to-be-processed object.

Further, according to the heat treatment apparatus of claim 2, since the gas introduction pipe is made of quartz glass, and a protective film made of SiC film is formed on the inner circumferential surface of the gas ejection hole formed in the tube wall, the gas introduction pipe is attached to the gas introduction pipe. When the foreign material is removed or cleaned by etching, the inner circumference of the thin gas ejection hole can be prevented from being crushed by etching, thereby improving durability and invariably immobilizing film forming conditions (gas ejection amount). Is promoted.

EXAMPLE

Next, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

3 is an explanatory view showing the configuration of a heat treatment apparatus according to an embodiment of the present invention.

11 is a quartz outer reaction tube which opened the lower end. Around the outer reaction tube 11, cylindrical resistive heaters 12 are arranged as heating means. The heater 12 is for heating the to-be-processed object and reaction gas which are demonstrated next.

The outer reaction tube 11 and the inner reaction tube 13 are each provided on a manifold 15 fixed to the base 14 to form a vertical furnace.

In the drawing, reference numeral 16 denotes a cover for blocking the lower end opening of the inner reaction tube 13. Insulating tube 17 is provided in the center of the upper surface of this cover body 16.

On this heat insulating tube 17, a quartz wafer boat 18 made of heat resistance is placed, and as the wafer boat 18, a plurality of semiconductor wafers (hereinafter referred to as wafers) W, which are a plurality of workpieces, are horizontally placed. It is also to be supported at regular intervals.

In addition, the rotary shaft 20 of the motor 19 mounted on the lid 16 is connected to the thermal insulation cylinder 17 on which the wafer boat 18 is placed, and the rotary shaft 20 and the thermal insulation cylinder 17 are connected. It rotates integrally.

A magnetic fluid seal or a magnetic coupling type shaft coupling is used as a normal sealing means 29 as a part for introducing this rotation into the inner reaction tube 13. For this reason, a leak of outside air does not occur in the inner reaction tube 13.

On the other hand, in order to grow a thin film without crystal defects uniformly over the entire surface of the wafer, the fresh reactant gas is uniformly supplied to the wafers W, respectively, and the waste gas is quickly discharged without convection on one side. Is very important.

Thus, one or more gas introductions are supported in the inner reaction tube 13 at regular intervals on the wafer boat 18 to supply the reaction gas in parallel between the wafers W along the surface of the wafer W. The tube 21 is formed.

The gas introduction pipe 21 is provided with a plurality of gas ejection holes at regular intervals so as to be located between the respective wafers W. As shown in FIG. The reaction gas is ejected from this gas ejection hole.

4 is a cross-sectional view showing the configuration of the gas introduction pipe 21. In the quartz gas introducing pipe 21, a plurality of gas ejection holes 21a, 21b, 21c, 21d and 21e have a predetermined interval along the axial direction of the gas introducing pipe 21. Formed. The gas ejection hole 21a is formed in the front end of the gas introduction pipe 21, and is formed in the order of the following gas ejection holes 21b, 21c, 21d, and 21e.

Further, the diameters d ₁ , d ₂ , d ₃ , d ₄ , and d ₅ of the holes of the gas ejection holes 21 a, 21 b, and 21 e are d ₁ d. ₂ d ₃ d ₄ d ₅ (e.g., 1.6 mm, 1.4 mm, 1.2 mm, 1.0 mm from the front end side). That is, the diameter of the hole becomes larger toward the front end of the gas introduction pipe.

In this way, the hole diameters d ₁ , d ₂ , and (d ₂ ) of the gas ejection holes 21 b, 21 c, 21 d, and 21 e formed at regular intervals along the axial direction of the gas introduction pipe 21. As d ₃ ), (d ₄ ) and (d ₅ ) become larger toward the front end of the gas introduction pipe, the pressure P in the gas introduction pipe 21 is reduced to the axis of the gas introduction pipe as shown in FIG. Almost constant in direction. Thereby, the ejection amount of the source gas ejected from each gas ejection hole 21b, 21c, 21d, and 21e can be made constant.

Here, as shown in FIG. 5, the hole diameters of the respective gas ejection holes 21'a, 21'b, 21'c, 21'd and 21'e are made constant. The number of holes of the gas ejection hole (for example, the gas ejection hole 21'a) formed in the front end side of the gas introduction pipe 21 'may be increased in the same plane as shown in FIG.

In this embodiment, an example in which the gas ejection holes are arranged at regular intervals is described. However, even if the upper interval is narrowed and the lower interval is widened, the raw material gases supplied to the upper and lower wafers W may be averaged. In other words, the gas ejection holes may be made uniform in the total opening area.

In addition, in the present embodiment, an apparatus for supplying the source gas downward and exhausting the exhaust gas from the bottom is explained. However, even if the inflow of the source gas is from the top and from the exhaust, the intrinsic uniformity should be obtained.

In addition, a plurality of gas suction exhaust holes 22 are formed on the inner surface of the inner reaction tube 13 facing the gas introduction tube 21. The gas introduction pipes 21 are formed at regular intervals corresponding to the gas ejection holes 21a to 21e.

7 shows the positional relationship between the gas inlet pipe 21 and the gas suction exhaust hole 22 formed by being drilled in the inner reaction tube 13 as an example.

7A shows a gas suction exhaust hole 22. Is an example formed by deviating from the half surface of the inner reaction tube 13 facing the gas introduction tube 21, and (b) of FIG. 7 is deviated over the entire surface of the inner reaction tube 13. This is an example formed by drilling. FIG. 7 (c) is an example in which a slit-shaped gas suction exhaust hole is formed in a half surface of the inner reaction tube 13, and FIG. 7 (d) likewise shows the entire surface of the inner reaction tube 13 This is an example formed by drilling a hole over.

As shown here as an example, the gas suction exhaust hole was formed in the half surface or the whole surface of the inner reaction tube 13. However, the present invention is not limited to this and may be formed by drilling a hole only in a portion of the open angle θ as shown in FIG.

These gas suction exhaust holes 22. Is connected to one or more exhaust nozzles 23 formed in the manifold 15 through the inner and outer reaction tubes 13 and 11.

That is, the reaction gas passing between the wafers W is the gas suction exhaust hole 22... With a suction pump (not shown). Is aspirated from. The exhaust nozzle 23 is exhausted between the inner reaction tube 13 and the outer reaction tube 11.

Incidentally, in the drawings, 24, 25, 26, 27, and 28 are seal members by keeping the inside of the furnace in an airtight state.

In the heat treatment apparatus configured as described above, heat treatment is performed on the wafer to explain the epitaxial growth of Si as an example.

First, the lid 16 is lowered by a lifting device (not shown), and the wafer wafer 18 made of quartz is taken out of the reaction tube. In this boat 18, a plurality of Si single crystal wafers W are transferred to and held on the wafer boat 18 at a predetermined interval, for example, 3/16 pitch.

Here, the lid 16 is lifted and pushed into the lower end opening of the inner reaction tube 13 so as to be in contact with the seal member 25.

Next, in this state, a heating current is supplied to the heater 12 to raise the wafer W accommodated in the inner reaction tube 13 to a predetermined temperature.

In addition, a 5 to 10 l / min flow of nitrogen gas flows from the gas introduction pipe 21 to exhaust the inside of the reaction tube until it becomes 10 ^-2 to 10 ^-3 Torr by a suction pump connected to the exhaust nozzle 23 to replace air. do.

Thereafter, the gas supply is stopped, and the replacement is carried out in a high vacuum state so that the pressure in the reaction tube is 10 ^-5 to 10 ^-6 Torr. In addition, 5-10 L / min of hydrogen gas is discharged to make the pressure in the reaction tube 1 to 2 Torr, thereby reducing the atmosphere. The hydrogen chloride gas is etched in hydrogen gas so as to be about 1 to 5% vo1. To etch the surface of the wafer.

Then, the native oxide film or the like formed on the surface of the wafer is removed. As a result, the clear and clean side of the wafer W is exposed. As the Si source gas, dichlorsilane (SiH ₂ Cl ₂ ) gas is mixed in 1 to 2 L / min, hydrogen gas 20 L / min and hydrogen gas 20 L / min to start epitaxial growth. At this time, hydrogen chloride may be flowed in a small amount (about 0.1 L / min). Then, the Si source gas or the like introduced into each wafer from the gas introducing pipe 21 passes between the wafers.

Subsequently, the Si source gas or the like is applied to the gas suction exhaust hole 22... Of the inner reaction tube 13 formed to face the gas introduction tube 21. It is sucked and exhausted from. At this time, the thermos (71) is rotated at a predetermined speed by the motor (19). As a result, the wafer boat 18 on which the wafer W is supported rotates.

Thus, the uniformity of the thickness of the thin film grown in the wafer surface is further improved. In addition, a small amount of doping gas is added to make the set conductivity at this time, that is, the specific resistance. After about 10 minutes of growth, an epitaxial layer of 2-5 μm is formed.

Thereafter, the Si source gas supply is stopped and the inside of the reaction tube is purged with hydrogen gas. After a few minutes, the temperature is lowered. Confirm that the inside of the reaction tube is 600 ± 200 ℃, and switch to purge of nitrogen gas. For a while, purge the nitrogen gas and evacuate it with the suction pump.]

Thereafter, the suction pump is stopped, and after confirming that the inside of the reaction tube has returned to atmospheric pressure, the lid 16 is lowered to take the wafer W out of the reaction tube. The growth of one time is completed by these series of operations.

After completion of one growth, the wafer boat or the like on which the wafer W is not placed again is lifted by the lid 16 as a lifting device to close the lower end opening of the inner reaction tube. Then, the suction pump connected to the exhaust nozzle 23 is operated.

In addition, the gas introduction pipe 21 is used to introduce a mixed gas of 1 to 20% vol. Of chlorine trifluoride (ClF ₃ ) of an argon gas base into the reaction tube and maintain it at about 100 to 150 Torr or more. In this case, the temperature is maintained at a constant temperature as 100 ~ 500 ℃.

By such means, dry etching is performed on the quartz jig, for example, Si attached to the wafer boat 18, the inner reaction tube 13, the gas introduction tube 21, or the like.

By this step, a pattern of a constant gas flow is formed in the ejection hole of the gas introduction pipe 21 or the gas ejection hole of the inner reaction tube 13 during each epitaxial growth.

This ensures the quality of the film and the uniformity of the film thickness formed on the wafer for each batch. However, it is preferable to perform the etching process by argon-based chlorine trifluoride after epitaxial growth every time. However, depending on the ratio of the flow rate of the reaction gas, it may be carried out once after several times of growth.

In addition, in the above-described embodiment, only the application of the present invention to the vertical furnace has been described, but it is a matter of course that the horizontal furnace is also applicable.

As described above, according to the heat treatment apparatus of the present invention, the following excellent effects can be obtained.

(1) According to the heat treatment apparatus according to claim 1, the opening area of the gas ejection hole formed in the pipe wall of the gas introducing pipe is provided at the base side of the gas introducing pipe so that the distribution of the gas ejection amount is constant along the longitudinal direction of the gas introducing pipe. The opening area of the exhaust hole formed in the pipe wall of the inner reaction tube is set to increase gradually toward the front strap end, and at the other end of the exhaust means to make the distribution of the gas exhaust amount along the longitudinal direction of the inner reaction tube constant. Since it is set to increase gradually toward the end, it becomes possible to form a flow of reaction gas parallel and uniform to each surface of a plurality of workpieces, and to form a uniform, high quality thin film on the surface of the workpiece. Become.

(2) According to the heat treatment apparatus according to claim 2, since the gas introduction pipe is made of quartz glass, and a protective film made of SiC film is formed on the inner circumferential surface of the gas ejection hole formed in the pipe wall, the gas introduction pipe is attached to the gas introduction pipe. When the foreign matter is removed or cleaned by etching, the inner circumference of the gas ejection hole, which is a thin portion, can be prevented from being crushed and enlarged by etching, thereby improving durability and invariably immobilizing the film forming conditions (9). It is planned.

Claims (2)

The inner reaction tube is mounted in the inner reaction tube provided in the outer reaction tube, and the plurality of target objects are mounted on the boat at predetermined intervals, and the target object is heated by heating means provided around the outer reaction tube. The reaction gas is supplied in parallel with the surface of the object to be processed from a plurality of gas ejection holes formed in the pipe wall of the gas introduction pipe inserted in the longitudinal direction therein, and the reaction is carried out from the plurality of exhaust holes formed in the pipe wall of the inner reaction tube. In the heat treatment apparatus for exhausting by means of the exhaust means at one end through the gap between the tube and the outer reaction tube, the opening area of the gas ejection hole formed in the tube wall of the gas introduction tube 21 of the gas introduction tube 21. It is designed to gradually increase from the source side of the gas introduction pipe 21 toward the front end so that the distribution of the gas ejection amount along the longitudinal direction becomes constant. At the same time, the opening area of the exhaust hole formed in the pipe wall of the inner reaction tube 13 is moved from one end to the other end of the exhaust means so that the distribution of the gas exhaust amount is constant along the longitudinal direction of the inner reaction tube 13. Heat treatment apparatus characterized in that it is set to gradually increase toward. The heat treatment apparatus according to claim 1, wherein the gas introduction pipe (21) is made of quartz glass, and a protective film made of a SiC film is formed on an inner circumferential surface of the gas ejection hole formed in the tube wall.

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