JP3874975B2 - High temperature and high pressure processing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for performing a heat treatment such as annealing on a product such as a semiconductor represented by ULSI that requires processing of an object to be processed even in a dust-free atmosphere while maintaining a uniform temperature in an atmosphere of a high-temperature and high-pressure gas. is there.
In particular, the present invention relates to an apparatus for performing processing while keeping soaking with a simple heater when plate-like products such as Si wafers are stacked in a shelf shape and annealed by batch processing.
[0002]
[Prior art]
As a vertical cylindrical apparatus for performing heat treatment in a high temperature and high pressure gas atmosphere using an inert gas such as argon in a batch system, a hot isostatic press apparatus (HIP apparatus) is well known. It is used to manufacture non-porous products in the powder metallurgy / ceramics field or the casting field. FIG. 4 shows an example of the structure of a typical HIP device.
A technical problem in an HIP apparatus or the like used in a high-temperature and high-pressure gas atmosphere is the arrangement of a heater for equalizing the temperature in the processing space. In other words, by controlling the temperature distribution that the upper part tends to become hot and the lower part tends to become cold due to intense natural convection caused by high density and low viscosity of the high-temperature and high-pressure gas, so as to equalize the predetermined space in the vertical direction Is required.
[0003]
Normally, as shown in FIG. 4 , the heater is arranged so as to surround the processed product from the side, and the heater is divided into a number of zones in the vertical direction in order to ensure heat uniformity. The temperature measuring means is disposed in the heater to detect the temperature, and the electric power supplied to each heater is controlled to perform the temperature equalization control.
In particular, high-pressure vessels (pressure vessels) increase in weight and cost as the diameter increases. From the concept of increasing the length in the vertical direction to increase the volume, there are many vertically long shapes, Soaking has been very important.
[0004]
In the case of the HIP apparatus having such a configuration, if the temperature is 1400 ° C. or lower, the heater is formed as a corrugated heater using a ceramic wire insulating insulator made of a metal wire or a strip-like element. A method of fixing to the support structure is adopted.
[0005]
[Problems to be solved by the invention]
In the case of a semiconductor such as ULSI, which is mainly targeted by the present invention, if dust or the like adheres to the object to be processed in the process, the electric circuit or the like formed on the surface of the product will be damaged. It is necessary that the environment is simultaneously formed.
The HIP apparatus shown in the prior art is usually intended for powder metallurgy, ceramics, cast products, and the like, and since dust is an accessory to these, no consideration is given to the absence of dust.
[0006]
In the field of ULSI semiconductors, since the apparatus is placed in a clean room, there is a demand for downsizing and weight reduction, short processing time, low apparatus cost, etc. Stronger than the metallurgical field.
Specifically, in order to reduce the size of the apparatus, the miniaturization of the high-pressure vessel is the most important, but it is difficult to cope with a structure like a conventional HIP apparatus.
That is, since the normal HIP apparatus is a vertical electric furnace as described above, the height of the processing chamber is larger than the diameter, and therefore, as shown in FIG. 4, it surrounds the processing chamber. An electric resistance wire heating type heater is arranged.
[0007]
In the case of ULSI, a standard processed product, that is, a wafer size is 200 mm (8 inches), and a wafer is handled by a cassette containing 25 sheets, so 25 sheets are often handled as one lot. In this case, in the process of performing batch processing, the processing is performed in a state of being stacked in a shelf shape at a pitch of 5 to 6.5 mm. Recently, it has been considered to process half of the 25 sheets as one lot.
In any case, the height for one lot is about 120 to 160 mm, which is smaller than the diameter of 200 mm. In the case of such a ratio of height to diameter, the heater is arranged so as to surround the processed product from the side surface, and the electric power supplied by dividing the heater into a plurality of stages is controlled in order to ensure thermal uniformity. There is a limit to downsizing in the configuration.
[0008]
In addition, since the overall size of the high-pressure vessel depends on the inner diameter of the high-pressure vessel, disposing a heater on the side surface has a limit in reducing the inner diameter of the high-pressure vessel.
Also, the heater usually has a structure in which a metal electric resistance wire element is fixed or suspended on an electrically insulating insulator such as ceramics. However, the generation of wear powder due to expansion / contraction due to the difference in thermal expansion coefficient between the two. In addition, wear powder due to vibration generated when AC is used for the supplied power is inevitably generated. However, in such a structure in which the heater is arranged at a higher position than the treated product, these wear powder is treated. There is a high possibility that the product falls on the product, that is, the treated product is contaminated.
[0009]
When batch processing is performed, a high-temperature and high-pressure gas process apparatus such as a conventional HIP apparatus is not suitable for heat treatment such as ULSI, and cannot be practically used for industrial production.
[0010]
[Means for Solving the Problems]
The present invention has been made to solve the above-described problems of the prior art. Specifically, the present invention was invented to perform high-temperature and high-pressure treatment while miniaturizing the apparatus and ensuring sufficient soaking for the required batch size.
First, a feature of the present invention is that in a high-temperature and high-pressure processing apparatus that performs processing in a high-temperature and high-pressure atmosphere by heating a plate-like object to be processed laminated in a processing chamber in a pressure vessel with a heater, the heater includes the processing object. It is that it is disposed in the processing chamber so as to be located only under the object.
[0011]
In the case of the structure in which the heater is arranged on the side surface of the object to be processed, it is inevitable that the inner diameter of the pressure vessel increases. However, by arranging the heater only below the object to be processed as in the present invention, the pressure vessel An increase in the inner diameter of the device can be suppressed, and thus the apparatus can be miniaturized.
In order to improve the heat uniformity in the processing chamber with the structure in which the heater is disposed only in the lower part, in the present invention, the heat treatment cylindrical body having an opening portion that is always opened up and down is further provided on the workpiece. It is disposed in the processing chamber so as to surround it.
[0012]
Usually (when there is no soaking cylinder), when heated with a heater from below, a temperature distribution is likely to occur where the upper part of the processing chamber is hot and the lower part is cold.
In the present invention, since the temperature equalizing cylinder is provided, an upward flow is generated inside the temperature equalizing cylinder due to the heat of the heater for heating the workpiece.
And since the opening part which always opens is provided in the upper and lower sides of a cylinder, a downward flow generate | occur | produces on the outer side of a cylinder, and a circulation convection arises inside and outside a cylinder. This circulating convection ensures thermal uniformity in the processing chamber.
[0013]
Note that the processing chamber refers to the inside of the heat insulating structure provided in the pressure vessel based on an embodiment described later, but is not limited thereto.
Further, when the present invention is viewed from another point of view, in the high-temperature and high-pressure processing apparatus that performs processing in a high-temperature and high-pressure atmosphere by heating a plate-like object to be processed stacked in the processing chamber in the pressure vessel with a heater, the heater Is disposed in the processing chamber so as to be positioned only below the workpiece, and is formed in the processing chamber so that at least the first flow path and the second flow path are always in communication with each other. The workpiece is positioned and an upward flow due to heating of the heater flows, and the second flow passage communicates with the first passage at the upper and lower portions of the processing chamber, and the downward flow flows through the first passage. It can also be said that the apparatus is a high-temperature and high-pressure treatment apparatus characterized in that circulation convection is generated between the first passage and the second passage.
[0014]
In this case, the upward flow flowing through the first flow passage flows into the second passage at the upper portion of the processing chamber, flows down to the lower portion of the processing chamber, flows into the first passage again, the first passage, the second passage, Circulating convection occurs between the two. This circulating convection ensures thermal uniformity in the processing chamber.
In addition, it is preferable that temperature measuring means is disposed inside the soaking cylinder. In other words, it can be said that temperature measuring means is disposed in the first flow path.
[0015]
In normal high-temperature and high-pressure operation, for example, it is possible to ensure a substantially uniform temperature under a high-pressure condition of 20 MPa or more. However, in order to guarantee the temperature history of the workpiece, It is important to monitor. In addition, when an operation for heating at a low pressure point is necessary, the heating rate of the heater can be controlled while monitoring the temperature distribution.
In addition, when the temperature is increased at high speed, a large amount of power may be supplied to the heater. In preparation for such a case, a temperature measuring unit is separately provided in the vicinity of the heater from the viewpoint of preventing overheating of the heater. It is also recommended to take measures to prevent this overheating by measuring the temperature in the vicinity.
[0016]
Further, it is preferable that a shielding member for shielding between the temperature-uniforming cylinder and the lower inner surface of the pressure vessel is provided. In other words, it can be said that the first and second passages are formed away from the lower inner surface of the pressure vessel.
Furthermore, it is preferred that the smoothing process by the electrolytic polishing method on a surface of at least one of the metallic member of the heating data and the soaking tubular member disposed in the pressure vessel is applied.
In order to suppress the generation of dust generated by oxidation of the metallic member, it is effective to perform a surface smoothing process such as electrolytic polishing so as to reduce the unevenness of the surface of these furnace components. This is because a phenomenon such as oxidation is noticeable at a pointed portion, and when such a portion is oxidized, it is easily peeled off.
[0017]
In addition, based on the below-described embodiment, the metallic member includes, in addition to the heater, a heat insulating structure, a soaking tube, and the like, but is not limited thereto.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a first embodiment of the present invention, which is a high-temperature and high-pressure processing apparatus 1 for a semiconductor. The apparatus 1 is for annealing a Si wafer as a workpiece 2 in a high-temperature and high-pressure gas atmosphere, and includes a pressure vessel (high-pressure vessel) 3 in which the wafer 2 is accommodated.
The pressure vessel 3 includes a cylindrical main body 4 having upper and lower openings, an upper lid 5 that closes an upper opening of the cylindrical main body 4, and a lower lid 6 that closes a lower opening of the cylindrical main body 4. Although not shown, a press frame for supporting an axial load acting on the upper and lower lids 5 and 6 is provided.
[0019]
A plurality of wafers 2 can be supported in the vertical direction by a jig 7 provided for the lower lid 6. The wafer is taken in and out by raising and lowering the lower lid 6 by an elevator mechanism (not shown).
A heat insulating structure 8 is suspended from the upper lid 5. The heat insulation structure 8 has a structure in which a plurality of metal bowl-shaped members are overlapped with a gap. The wafer 2 is stacked in a shelf shape by a jig 7 inside the innermost surface of the heat insulating structure 8.
The heat insulation structure 8 is fixed by screwing into the opening inside the pressure vessel of the high pressure gas introduction hole 10 provided in the upper lid 5.
[0020]
The high pressure gas which is a pressure medium is supplied by a gas compressor using a (gas cylinder) as a gas source. In the case of a high pressure annealing method for preventing the generation of pores in the metal wiring film, an inert gas such as a high pressure argon gas of 200 MPa is used.
The high-pressure gas supplied from the high-pressure gas introduction hole 10 is introduced into the processing chamber space (inside the heat insulation structure) through a hole penetrating the heat insulation structure 8, but the gas is released as shown by an arrow in FIG. A structure in which gas is once dispersed in the horizontal plane direction and blown from the gas dispersion port 11 is preferable from the viewpoint of preventing movement of the semiconductor wafer 2 (wafer dance) during high-speed pressurization.
[0021]
In addition, it is preferable to arrange | position the gas distribution board 12 at intervals from the upper surface inside a heat insulation structure.
The gas is released from the processing chamber through a high-pressure gas discharge hole 13 formed in the upper lid 5. The gas in the processing chamber is guided to the high-pressure gas discharge hole 13 through the gas passage between the outside of the heat insulating structure 8 and the cylindrical body 4.
Below the wafer 2, an electric resistance wire heating type heater 15 is disposed. The heater 15 performs heating for high-temperature and high-pressure annealing. The heater 15 is fixed to the lower lid 6 via a support member 16, and is divided into two zones (heater elements 15a and 15b) in the radially inner and outer directions. If independent temperature control is performed for each of the heater elements 15a and 15b, it is possible to ensure soaking in the inner and outer diameter directions.
[0022]
The space between the inner surface of the heat insulating structure 8 and the object to be processed 2 controls the natural convection of high-temperature and high-pressure gas to prevent the vertical temperature distribution in the space in which the object to be processed is stored. It has a function to do. Specifically, soaking is performed by utilizing the phenomenon described below.
A process medium gas such as high-temperature and high-pressure argon has a high density and a low viscosity, so that it is very easy to generate natural convection, and the gas heated below rapidly rises to heat the workpiece 2. However, since the heat insulating structure 8 has an inverted saddle shape, the heated high temperature gas stays in the upper part of the space formed by the heat insulating structure 8 and has a temperature distribution in which the upper part is hot and the lower part is low. Likely to happen.
[0023]
This promotes this phenomenon because there is heat radiation from the inner surface of the heat insulating structure 8 to the outside, particularly from the inner surface of the cylindrical portion.
In the present embodiment, in order to prevent this phenomenon, a cylindrical soaking tube 17 that is opened up and down is disposed between the workpiece 2 and the heat insulating structure 8. The heat insulating structure 8 is disposed so as to surround the workpiece 2 from the side from the uppermost workpiece 2 to the lowermost workpiece 2.
Due to this soaking cylinder 17, the natural convection of the gas becomes an upward flow inside the cylindrical body 17 and a downward flow outside. The heat from the heater 15 is first supplied to heat and heat the workpiece 2, and then the heat inside the heat insulating structure 8 is compensated for heat radiation from the inner surface to the outside to maintain the temperature inside the processing chamber.
[0024]
From a different viewpoint, the inside of the soaking cylinder 17 constitutes a first flow passage S1 through which an upward flow flows, and the outside of the cylinder 17 constitutes a second passage S2 through which a downward flow flows. It can be said that the convection which circulates up and down between 1 passage S1 and the 2nd passage has arisen.
FIG. 2 shows the state of gas flow when the soaking cylinder 17 is not provided as a comparative example. Natural convection becomes local and the upper part tends to become high temperature. In FIG. 2, the temperature distribution in the radial direction is likely to be biased, but the temperature distribution in the radial direction in FIG. 1 can be made more uniform.
[0025]
In the state of storing 13 8-inch wafers, the temperature distribution in the structure of the present invention shown in FIG. 1 and the structure of the comparative example shown in FIG. At that time, in the structure of the comparative example, the temperature difference between the upper end portion and the lower end portion was 15 ° C., but in the structure of the present invention, it was 3 ° C. Usually, the temperature distribution in the heat treatment of such a Si wafer is set to ± 5 ° C. or less. With the structure of the present invention, it is possible to sufficiently satisfy such a temperature distribution specification.
The shape and arrangement of the soaking tube 17 are not particularly limited as long as the above phenomenon can be exhibited, and is not limited to the illustrated one. However, it is preferable that the entire object to be processed is enclosed and the side surface of the heater is completely accommodated inside the soaking cylinder 17. The temperature equalizing cylinder 17 is opened in the vertical direction, that is, the upper end and the lower end of the temperature equalizing cylinder 17 are directed from the outside to the inside of the temperature equalizing cylinder 17 or from the inside to the outside. It is necessary to be open so that a flow of water is formed.
[0026]
However, the upper and lower openings for opening inside and outside need not be formed on the upper surface and the lower surface of the cylindrical body 17 as shown in FIG. Also good. For example, the lower end portion of the cylindrical body 17 is extended to the vicinity of the lower lid 6, an opening is provided in the lower part of the temperature equalizing cylinder corresponding to the side portion of the heater 15, and the high temperature that has descended outside the temperature equalizing cylinder 17. A configuration in which a high-pressure gas is allowed to flow into the heater 15 is also included in the aspect of the present invention.
The cylindrical body 17 may be a simple cylinder as shown in FIG. 1, but depending on the degree of heat dissipation upward of the heat insulating structure 8, etc., as shown in FIG. It is good also as a structure narrowed down like this.
[0027]
Further, from another point of view, the member for equalizing the temperature need not be the cylindrical body 17, and the first flow passage S1 through which the upward flow flows and the second flow passage S2 through which the downward flow flows are formed. Just do it.
The heater 15 for heating the object to be processed 2 and the object to be processed 2 are fixed on the lower lid 6, and the Si wafer as the object to be processed 2 is taken in and out by raising and lowering the lower lid 6. The temperature equalizing cylinder 17 can be fixed to the lower lid 6, but it is usually performed by moving the Si wafer horizontally from the side by a robot or the like when the Si wafer is put in and out. Since fixing the temperature-uniforming cylinder 17 to the lower lid 6 requires an operation of removing the temperature-uniforming cylinder 17 at this time, it is recommended that the structure be suspended from the inner surface of the heat insulating structure 8. Is done.
[0028]
Further, the temperature distribution in the processing chamber is monitored by arranging temperature measuring means 20 and 21 exemplified by thermocouples at the upper end and lower end of the workpiece 2 inside the temperature equalizing cylinder 17. Is recommended (see FIG. 3). In normal high-temperature and high-pressure operation, it is possible to ensure the soaking property as described above under a high-pressure condition of 30 MPa or more. However, in order to guarantee the temperature history of the workpiece 2, It is important to monitor the temperature throughout the process, and when an operation such as heating at a low pressure is necessary, it is recommended to control the temperature rising rate while monitoring the upper and lower temperature distribution. When the temperature is increased at a high speed, large power may be supplied to the heater 15 in some cases. In such a case, from the viewpoint of preventing the heater 15 from being overheated, it is also recommended that a separate temperature measuring means 22 be disposed in the vicinity of the heater and measures should be taken to prevent this overheating by measuring the temperature in the vicinity of the heater. (See FIG. 3).
[0029]
In the high-temperature and high-pressure gas annealing apparatus 1 for a semiconductor substrate of the present embodiment, the next problem after the temperature distribution is prevention of dust (particle) adhesion to the Si wafer. Dust is generated due to oxidation of furnace components such as heat insulation structures and friction and vibration between parts. In the case of fine and light dust, it is increased by increasing buoyancy with high-density high-pressure gas and easily floats. The generated dust is carried to the object storage space by natural convection of the gas. To prevent this, the following considerations are recommended.
First, in many cases, such dust tends to accumulate below the inside of the container, more specifically, on the lower lid. Therefore, it is one measure to provide a shielding plate (shielding member) 25 so that the downward flow outside the natural convection soaking cylinder 17 does not reach the upper surface of the lower lid 6. The shielding plate 25 is provided between the soaking tube 17 and the lower lid 6 (the inner surface of the lower part of the pressure vessel 3). In other words, in the form shown in FIG. 1, the first and second circulation furnaces S <b> 1 and S <b> 2 are separated from the upper surface of the upper lid 6 by being separated by the shielding plate 25.
[0030]
Further, when the heater 15 is heated by alternating current, when the heater element is a strip or wire, vibration is generated and dust is generated due to friction with the fixed electrically insulating insulator. Recommended.
For the heat insulating structure 8, a felt-like heat insulating material is usually used. However, most of the felt-like heat insulating materials are mainly ceramic fibers, which are embrittled and generate dust by repeated temperature cycles. In order to prevent this and to obtain a practically sufficient heat insulating property, as shown in FIG. 1, as shown in FIG. It is most suitable to do. If the temperature is up to about 500 ° C., a practically sufficient heat insulating function can be obtained by manufacturing a reverse shielded heat shielding member made of austenitic stainless steel such as SUS304 and stacking three to five layers. When overlapping, it is recommended to provide a gap of 2 to 3 mm so that they do not rub against each other and fix them so that they do not rattle.
[0031]
In addition, if the heat insulation structure 8 is a member in which heat insulation is possible, it will not be limited to said thing.
Furthermore, in order to suppress the generation of dust generated by the oxidation of the heater element, the heat insulating structure 8 may be subjected to a surface smoothing process such as electrolytic polishing so as to reduce the unevenness of the surface of these furnace components. It is effective. This is because a phenomenon such as oxidation is noticeable at a pointed portion, and when such a portion is oxidized, it is easily peeled off.
According to the above embodiment, in the case of an apparatus for 8-inch wafers, the inner diameter of the high-pressure vessel 3 is 350 to 300 mm in the conventional HIP apparatus, but about 300 mm is sufficient. In other words, the pressure receiving area can be reduced by 30 to 40%, and the weight reduction effect as well as the size of the high pressure vessel is very large. Further, the amount of the pressure medium gas required for the processing can be reduced at the same ratio, and the improvement effect on the processing cost is extremely large.
[0032]
According to the present apparatus 1, contact holes, via holes, and trenches in copper wiring, which are being used in conjunction with the recent miniaturization of ULSI wiring films and low electrical resistance, are improved in filling and adhesion. It becomes possible to apply a high-pressure gas annealing process. In other words, the HIP processing method that has already been proven in reliability improvement and yield improvement by removing hole defects in the casting field can be used in the ULSI semiconductor manufacturing field, and high reliability and cost reduction are becoming a great demand. It is expected to make a significant contribution in this area.
[0033]
【The invention's effect】
According to the present invention, it is possible to ensure uniform temperature while reducing the size of the apparatus.
[Brief description of the drawings]
FIG. 1 is an internal cross-sectional view of a high-temperature and high-pressure processing apparatus of the present invention.
FIG. 2 is an internal cross-sectional view of a high-temperature and high-pressure processing apparatus as a comparative example.
FIG. 3 is an internal sectional view mainly showing an arrangement of temperature measuring means.
FIG. 4 is an internal cross-sectional view of a conventional HIP device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 High temperature high pressure processing apparatus 2 To-be-processed object 3 Pressure vessel 8 Heat insulation structure 15 Heater 17 Soaking | uniform-heating cylinder 25 Shielding member S1 1st flow path S2 2nd flow path 20 Temperature measurement means 21 Temperature measurement means 22 Temperature measurement means

Claims (8)

In a high-temperature and high-pressure processing apparatus that performs processing in a high-temperature and high-pressure atmosphere by heating a plate-like object (2) stacked in a processing chamber in a pressure vessel (3) with a heater (15),
The heater (15) is disposed in the processing chamber so as to be positioned only below the workpiece (2),
A high-temperature and high-pressure treatment apparatus, characterized in that a soaking tube (17) having an opening that is always open vertically is disposed in the treatment chamber so as to surround the workpiece (2). The high-temperature and high-pressure processing apparatus according to claim 1, wherein temperature measuring means (20, 21) is disposed inside the soaking tube (17). The high temperature according to claim 1 or 2, wherein a shielding member (25) is provided for shielding between the soaking tube (17) and the lower inner surface (6) of the pressure vessel (3). High pressure processing equipment. In a high-temperature and high-pressure processing apparatus that performs processing in a high-temperature and high-pressure atmosphere by heating a plate-like object (2) stacked in a processing chamber in a pressure vessel (3) with a heater (15),
The heater (15) is disposed in the processing chamber so as to be positioned only below the workpiece (2),
In the processing chamber, at least the first flow path (S1) and the second flow path (S2) are formed so as to always communicate ,
The workpiece (2) is positioned in the first flow path (S1), and an upward flow due to heating of the heater (15) flows. The second flow path (S2) is above and below the processing chamber. In this way, a circulating convection is generated between the first passage (S1) and the second passage (S2) when the downward flow flows in communication with the first passage (S1). High pressure processing equipment. The high-temperature and high-pressure processing apparatus according to claim 4, wherein temperature measuring means (20, 21) is disposed in the first flow path (S1). The high-temperature and high-pressure processing apparatus according to claim 4 or 5, wherein the first and second passages (S1, S2) are formed away from the lower inner surface (6) of the pressure vessel (3). The high-temperature and high-pressure processing apparatus according to any one of claims 1 to 6, wherein a temperature measuring means (22) for detecting heater overheating is disposed in the vicinity of the heater (15). Wherein the smoothing process by the electrolytic polishing method on a surface of at least one of the metallic members disposed by said heating data and the soaking tubular body is subjected to the pressure vessel (3) in The high-temperature / high-pressure processing apparatus according to any one of claims 1 to 7.

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