JPH0612825Y2 - Evaporator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an evaporator for vaporizing a liquid raw material such as a semiconductor layer forming material used for manufacturing a semiconductor.

[Conventional technology]

In a semiconductor manufacturing process, a layer made of an insulating film semiconductor material is formed on the surface of a wafer, and tetraethyloxide silane (hereinafter abbreviated as TEOS) is included in such a material. This TEOS is
It has a high boiling point of 170 ° C and is difficult to vaporize, and has the property of decomposing at a temperature of about 130 ° C. Generally, it is supplied to the processing chamber for forming an insulating semiconductor layer by a bubbling method or a baking method. There is. Of the above methods,
The bubbling method is as shown in FIG. 3, and TEOS is held in a raw material tank 2 arranged inside the heating chamber 1 in a state where the temperature is strictly controlled, and the mass flow is performed in the raw material tank 2. Controller (hereinafter abbreviated as MFC) 3
Inert gas whose flow rate is controlled by (eg N ₂ , Ar)
TEOS is bubbled by supplying as a carrier gas, the vaporized gas generated in the raw material tank 2 is
It is adapted to be fed into the processing chamber 5 through the pipe 4. Then, this vaporized gas is sprayed on the surface of the wafer 6 arranged in parallel in the processing chamber 5 to form an insulating semiconductor layer. The baking method is as shown in FIG. 4, in which the raw material tank 2 is arranged in the heating chamber 1a whose temperature is adjusted, and the MFC 3 is arranged in the heating chamber 1a at the downstream side. The TEOS sent from the raw material tank 2 is sent into the processing chamber 5 in which the wafers 6 are juxtaposed by the MFC 3 while adjusting the flow rate. In FIGS. 3 and 4, 7 is an on-off valve, 8 is a pressure gauge, and 9 is a variable flow valve.

[Problems to be solved by the invention]

However, in the above bubbling method, vaporized TEOS is used.
Is sent to the processing chamber 5 in a state of being mixed with an inert gas, so that its concentration becomes low and it becomes difficult to measure the supply amount of TEOS. Therefore, there is a problem that it takes a long time to form the insulating semiconductor layer and the accuracy of the formed layer deteriorates. In addition, since it is necessary to strictly control the temperature of the heating chamber 1, there is a problem that the operation is difficult.
In the baking method, the accuracy of the forming layer is good, and it is not necessary to strictly control the temperature of the heating chamber 1a. However, in order to increase the vaporization amount of liquid raw material per unit time,
It is necessary to increase the vaporized surface area of the liquid raw material and increase the heating area of the liquid raw material to increase the amount of heat received by the liquid raw material per unit time. For this,
It is necessary to increase the size of the raw material tank 2 to increase the area of the bottom surface of the tank serving as the heating surface, and at the same time increase the surface area of the liquid raw material. Further, since the large raw material tank 2 is arranged in the heating chamber 1a, the heating chamber 1a becomes large.

The present invention has been made in view of such circumstances, and an object thereof is to provide an evaporator capable of downsizing the heating means and efficiently vaporizing the heating means while maintaining the advantages of the baking method. To do.

[Means for solving problems]

In order to achieve the above-mentioned object, the evaporator of the present invention has a liquid raw material supply pipe extending from a liquid raw material tank, the front end of which is connected to the lower end of a sealed chamber, and a heating means provided below the sealed chamber. And an evaporator that heats and vaporizes the liquid raw material sent from the liquid raw material tank in the sealed chamber and sends the vaporized raw material to the processing chamber through a gas raw material extraction pipe extending from the upper end of the sealed chamber. The bottom of the hermetically sealed chamber is formed in a circular stepwise shape that is gradually lowered toward the outside, centering on the injection opening to which the tip of the liquid raw material supply pipe is connected, and the stepped shape is formed. At the edge of each step, a ring-shaped weir is provided along the edge, and above the bottom surface, a disk-shaped shield plate for preventing liquid material scattering is provided. Passing the vaporized raw material between the inner wall and ceiling surface A configuration that is formed in the passage of use.

[Action]

That is, the evaporator of the present invention, like the conventional example, bubbling a liquid raw material heated and held by an inert gas to take out vaporized gas generated at that time, or heat a raw material tank in a large heating chamber. By doing so, the liquid raw material is not vaporized and taken out, but the liquid raw material supply pipe extending from the raw material tank is connected to the heated and held sealed chamber, and the liquid raw material sent from the raw material tank is vaporized in this sealed chamber. After that, it is fed into the processing chamber through a pipe for taking out the gas raw material. Therefore, the sealed chamber can be downsized, and the heating means for heating it can be downsized significantly. As a result, the large-sized heating chamber as in the conventional example becomes unnecessary. That is, since the bottom surface of the sealed chamber is formed in a circular step shape that is gradually lowered toward the outside with the injection opening as the center, and a weir is provided at the edge of each step, The liquid raw material spreads over almost the entire bottom surface and its surface area increases, so that heat transfer to the liquid raw material is improved. As a result, the liquid raw material can be effectively vaporized, and the sealed chamber can be downsized. In addition, since a disc-shaped shield plate for preventing the scattering of the liquid raw material is provided above the bottom surface, the liquid raw material sent into the sealed chamber through the injection opening scatters and mixes with the vaporized gaseous raw material in the sealed chamber. In such a state, it is prevented that the gas raw material is delivered to the pipe for taking out the gas raw material. Therefore, only the vaporized raw material containing no liquid passes through the passage for the vaporized raw material formed between the disc-shaped shield plate and the inner peripheral wall and ceiling surface of the sealed chamber, and the pipe for taking out the gaseous raw material. And is sent to the processing chamber through the pipe for extracting the gaseous raw material. Further, since the carrier gas is not used, there is no problem that the vaporized raw material is diluted.

Next, this invention will be described in detail based on embodiments.

〔Example〕

FIG. 1 shows an embodiment of this invention. That is, in the figure, 10 is a raw material tank, and the liquid TEOS for forming an insulating semiconductor layer is filled in the inner lower part side. A pipe 11 for supplying helium gas is connected to an upper end portion of the raw material tank 10, and the helium gas sent from the pipe 11 into the upper space of the raw material tank 10 causes the inside of the raw material tank 10 to be filled. TEOS is maintained in a stable state that is difficult to decompose. Reference numeral 12 is a pressure control valve provided in the pipe 11, and is a TE in the raw material tank 10.
When the OS decreases and the pressure in the raw material tank 10 decreases, the raw material tank 10 automatically opens, and helium gas is fed into the raw material tank 10. 13 and 14 are stop valves, 15 is a filter, 16 is a pressure nozzle, and 17 is a pressure indicating alarm meter. Reference numeral 18 denotes a raw material take-out pipe extending upward from the bottom side in the raw material tank 10 and penetrating through the ceiling portion to the outside, and the tip ends of the stop valves 19 and 20, the filter 22.
And, it is connected to the center of the bottom of the circular box-shaped sealed chamber 24 via the MFC 23 and the like. This sealed chamber 24 is
As shown in FIG. 2, the central portion side of the bottom surface portion 25 is in a state of being bulged upward, and a nozzle portion 26 having a discharge port 26a having a small diameter (diameter of 0.3 mm) is formed in the central portion thereof. While being planted, the upper surface of the bottom surface portion 25 is formed in a stepwise shape that is gradually lowered toward the outside with the nozzle portion 26 as the center. Then, a ring-shaped weir 27 having the same height is provided so as to project upward along the circumference at the edge of each step portion of the stepped bottom surface. Reference numeral 28 denotes a shield plate disposed above the bottom surface portion 25 at a predetermined distance from the bottom surface portion 25. The center portion 28a projects upward and the lower surface side thereof is a concave portion 28b for repelling the discharged liquid. Is formed in. The opening-side edge portion 28c of the recess 28b is formed in a sharp shape protruding downward and allows the liquid repelled by the recess 28b to drop right below without being transmitted to the lower surface of the shield plate 28. I'm running. The shield plate 28 has a ceiling 30 of the sealed chamber 24 due to the support 29 having a short cylindrical shape.
Is fixed to the lower surface of the
Holes 29a are provided at regular intervals along the circumference.
Reference numeral 31 is a hole portion provided in the central portion of the ceiling portion 30 for taking out the vaporized raw material. In addition, above and below the sealed chamber 24,
As shown in FIG. 1, a heater 32 is provided, and the heat generated by the heater 32 causes the sealed chamber 24 to move.
The inside is kept at a temperature of about 90 ° C. Therefore, from the raw material tank 10 to the sealed chamber 24 via the raw material take-out pipe 18.
Liquid TEOS sent to the lower side of the
It comes in contact with the stepped bottom surface of the bottom surface portion 25 heated by 2 and slowly descends in the sealed chamber 24 while spreading outward toward the outside. In the meantime, the liquid TEOS is heated and evaporated, and the vaporized gas moves to the upper portion on the peripheral wall side of the sealed chamber 24, passes through the hole 29a, and rises from the upper end of the central portion of the sealed chamber 24 to the hole 31. To go. In FIG. 1, 33 is a pipe for carrying vaporized gas, which extends from the center of the upper end of the sealed chamber 24, one end of which is fitted into a hole 31 provided in the ceiling portion 30 of the sealed chamber 24 and the other end of which is connected. Through the stop valve 34
It is connected to 5. This processing chamber 35 has a vacuum pump 36.
The inside of the pipe 33 is made to have a negative pressure by the action of the vacuum pump 36, and the vaporized gas in the sealed chamber 24 is supplied to the pipe 3
Aspirate through 3 In addition, 37 is an exhaust pipe branched from the pipe 33, and joins with an exhaust pipe 38 branched from the pipe 11, and the tip thereof extends to the outside. 39, 40, 41 are stop valves,
Reference numeral 42 is a heat insulating layer surrounding the pipe 33 and the exhaust pipe 37. Further, 43 is a temperature indicator controller provided in the heat retaining layer 42, 44 is a temperature indicator controller provided in the heater 32, and 45 is a liquid level gauge provided in the raw material tank 10.

In this configuration, first, the stop valves 13, 14, 20
And 34 are opened, and stop valves 39, 40,
41 is closed, and helium gas is 0.1 to 0.2 kg / cm ² G
It is sent to the raw material tank 10 at a pressure of. In that state, when the vacuum pump 36 of the processing chamber 35 is operated, the raw material tank 1
The liquid TEOS in 0 is sent into the sealed chamber 24 through the raw material extracting pipe 18, and is heated while the stepped bottom surface in the sealed chamber 24 is moved from the central portion toward the outer peripheral side and is effective. Vaporize. At that time, since the shield plate 28 is provided in the sealed chamber 24, the nozzle portion 26 moves the sealed chamber 2
Even if the liquid TEOS discharged into the inside 4 is scattered into the sealed chamber 24, it collides with the wall surface of the recess 28b of the shield plate 28 and is dropped downward. Therefore, while flowing on the stepped bottom surface of the bottom surface portion 25, only the vaporized TEOS vaporized by the heating of the heater 32 moves to the upper portion on the peripheral wall side in the sealed chamber 24. Then, the vaporized TEOS is sent to the processing chamber 35 via the pipe 33. As a result, the vaporized gas of TEOS is sprayed on the surface of the wafers arranged in parallel in the processing chamber 35, and an insulating semiconductor layer is formed on the surface. In addition,
The liquid TEOS sent into the sealed chamber 24 is MF.
Since the flow rate is adjusted to an appropriate value by C23, the sealed chamber 2
The vaporized TEOS vaporized in 4 and sent to the processing chamber 35 also has an appropriate amount, and the formed insulating semiconductor layer is in a good and accurate state.

As described above, in this evaporator, the sealed chamber 24 is remarkably downsized, and the bottom portion 25 of the downsized sealed chamber 24 is heated by the heater 32. Therefore, the heating means is remarkably downsized. You can That is, the sealed chamber 2
The miniaturization of No. 4 is achieved by forming the upper surface of the bottom surface portion 25 toward the outside in a stepwise shape gradually lowering and providing the weir 27 at the edge of each stepped portion. . That is, if the bottom surface portion 25 is simply made into an inclined surface without forming the stepped shape with the weir 27 as described above, the liquid TEOS fed into the inside from the nozzle portion 26 of the hermetically sealed chamber 24 streaks the inclined surface. It flows eccentrically and flows quickly, and accumulates in an annular shape at the peripheral edge, which is the lowest part of the slope. Therefore, the vaporization of the liquid TEOS is only performed in the uneven streak-like flow and the annularly accumulated portion, and the contact area with the heated bottom portion 25 becomes small. On the other hand, as described above, when the slope is formed in multiple stages with the weir 27, the liquid TEOS fed from the nozzle portion 26 concentrically sequentially fills each stage and flows out to the next stage, and the bottom face is formed. While extending to the entire part 25, it reaches the peripheral part which is the lowest part. This allows liquid TE
Since the OS spreads thinly in each step and contacts substantially the entire bottom surface portion 25 that is heated and is vaporized in that state, the vaporization efficiency becomes very high. Further, by inclining the bottom surface portion 25 from the center to the outside, the liquid TEOS is caused to flow along the inclination, and reaches the maximum temperature on the lowermost side to be vaporized and sent to the pipe 33. The temperature of TEOS is gradually increased. Therefore, the effective vaporization as described above becomes possible. Furthermore, liquid T
By adjusting the MFC 23, EOS is sent into the sealed chamber 24 at an appropriate flow rate, and within the sealed chamber 24, the shielding plate 28 prevents the EOS from being scattered and mixed with the vaporized gas. As a result, only the vaporized gas containing no liquid is taken out as a raw material, and the insulating semiconductor layer can be formed with good accuracy and good quality. Further, since the raw material tank 10 can be placed outside the heating chamber, TEOS that is unstable at high temperatures can be held in a stable state. Also, TEOS is used because carrier gas is not used.
There is no problem such as diluting.

At the time of stop, the stop valves 20 and 34 are closed. Further, when the operation is restarted, the stop valve 34 is closed and the stop valve 39 is opened, and in that state, the same operation as in the above-described embodiment is performed, and the inside of the sealed chamber 24 and the pipe 1 are operated.
The residual TEOS such as 8, 33 is removed from the exhaust pipe 37. Then, after the sent TEOS has reached a proper state, the stop valve 39 is closed and the stop valve 34 is opened to send the TEOS to the processing chamber 35. Further, a known gas-liquid separation device may be provided between the sealed chamber 32 and the processing chamber 35, and the vaporized gas flowing through the pipe 33 may be strictly gas. In this case, a pipe is extended from the gas-liquid separator to the raw material tank 10 so that the separated liquid component is sent to the raw material tank 10. Further, the liquid raw material used in the present invention is not limited to the above TEOS, and may be any liquid raw material that requires vaporization.

[Effect of device]

As described above, the evaporator of the present invention is provided with the heat-sealed sealed chamber on the downstream side of the raw material tank, and the liquid raw material sent from the raw material tank is vaporized in this sealed chamber and taken out to the outside. . Therefore, the liquid raw material can be effectively vaporized, and the heating means can be simplified and miniaturized. Further, since the carrier gas is not used, there is no problem that the raw material is diluted.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a partially cutaway sectional view showing a main part thereof, and FIGS. 3 and 4 are block diagrams of a conventional example. 10 ... Raw material tank, 18 ... Raw material extraction pipe, 24 ...
... Sealing chamber, 25 ... Bottom part, 26 ... Nozzle part, 27 ...
… Weir, 28 …… Shield plate, 33 …… Pipe, 35 …… Processing room

Claims (1)

[Scope of utility model registration request] 1. A liquid raw material supply pipe is extended from a liquid raw material tank, and its tip is connected to a lower end of a hermetically sealed chamber.
A heating means is provided on the lower side of the sealed chamber, the liquid raw material sent from the liquid raw material tank is heated and evaporated in the sealed chamber, and the vaporized raw material is passed through a gas raw material extracting pipe extending from the upper end of the sealed chamber. An evaporator sent to the processing chamber,
The bottom surface of the sealed chamber is formed in a circular stepwise shape that is gradually lowered toward the outside with the injection opening to which the tip of the liquid raw material supply pipe is connected as the center, and each of the stepped shapes. A ring-shaped weir is provided along the edge of the step, and a disc-shaped shield plate for preventing liquid raw material scattering is provided above the bottom surface. An evaporator characterized in that a passage for passing vaporized raw material is formed between the peripheral wall and the ceiling surface.