JP2000202275A - High temperature and high pressure gas treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of treating high temperature and high pressure gas in which a reduction in time in a cooling/pressure reducing process is attained when a semiconductor is treated by gas at high temperature and under high pressure, thereby enabling increasing a treating rate in high temperature and high pressure gas treatment of the semiconductor of high quality. SOLUTION: In a cooling/pressure reducing process, cold release is started while still in a high pressure state, and at a point of time when a treating chamber reaches prescribed temperature/prescribed pressure, a reduction in pressure is started. The starting time for reducing pressure is determined based on an empirical law taking handling temperature as an object. In this way, effective temperature drop is obtained, and when pressure is reduced to atmospheric pressure, excess temperature drop is not caused. As a result, a semiconductor of good quality can be treated in an extremely short time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-temperature and high-pressure gas processing method for processing a semiconductor in a high-temperature and high-pressure gas atmosphere.

[0002]

2. Description of the Related Art Conventionally, as a so-called pressure embedding method (high-pressure reflow process) of a wiring film, a semiconductor wafer having a concave portion on its surface is loaded into a processing chamber in a pressure vessel, and the processing chamber is heated to a high temperature by a heater. Heating and filling with inert gas such as argon gas to high pressure (heating / pressurizing step)
Next, the high-temperature and high-pressure state is held for a predetermined time (holding step), and then, over a predetermined time, heating suppression or stop control of the heater and gas recovery are performed (cooling / decompression step).
After that, a processing method is known in which a semiconductor in which a wiring film made of an aluminum alloy or the like is embedded is removed from a pressure vessel (see Japanese Patent Application Laid-Open No. 7-193630).

[0003]

In the above-described processing method, the cooling and depressurization steps are performed because a high-temperature processing environment of several hundred degrees Celsius and a high-pressure processing environment exceeding tens of MPa are created in the heating and pressing steps. In the process, it is necessary to cool the processing chamber (that is, the object to be processed) to a temperature that can be handled below 100 ° C., and to take a considerable time to return to the atmospheric pressure. Had been difficult. The reason is roughly as follows.

For example, as shown in FIG. 5, it is assumed that the temperature of the processing chamber is 700 ° C. and 150 MPa at the end of the holding step, and the power supply to the heater is cut off from the high-temperature and high-pressure state and the cooling is allowed to cool. Then, wait until it cools down to around room temperature and then start decompression.
The cooling rate under a high-pressure environment can be performed in a relatively short time due to the good heat radiation property of the high-pressure gas, but the gas density drops when the decompression is started after the room temperature environment is reached, that is, in the processing chamber. The substantial increase in the volume of gas at a stroke causes a remarkable temperature drop due to adiabatic expansion, which leads to a situation in which the gas temperature around the object to be processed is reduced to 0 ° C. or less.

If the object to be processed is taken out of the pressure vessel in this state, water vapor in the air will condense and generate water droplets on the surface of the object to be processed. Therefore, in order to prevent this, it is necessary to wait until the temperature of the object to be processed recovers to around room temperature. As a result, the entire processing time is long. On the other hand, as shown in FIG.
Assuming that the pressure was 0 MPa, not only turning off the power supply to the heater from this high temperature and high pressure state, but also starting the decompression at the same time, the cooling accompanying the good heat radiation of the high pressure gas was performed. Even though the situation is the same as that in FIG. 5, the processing chamber reaches the atmospheric pressure faster than the progress of the cooling, so that the gas density decreases, that is,
This means that the temperature drop caused by the adiabatic expansion due to the increase in the gas volume cannot be fully utilized.

Accordingly, when the temperature drop due to the adiabatic expansion is completed, the temperature of the processing chamber is still around 300 ° C., but the temperature drop after that depends on the heat radiation of the gas. Disappears. However, in the state where the processing chamber has been brought to the atmospheric pressure, the property that the heat radiation of the gas deteriorates appears on the front side, so that the gas temperature in the vicinity of the object to be processed hardly decreases. Was extremely long.
If it is not necessary to set the processing chamber to a high pressure environment,
A method of promoting cooling by circulating gas in the processing chamber is also conceivable. However, if this method is performed in a processing chamber in a high-pressure environment, even if the impurity component contained in the gas is as small as 10 ppm, for example, This is comparable to a polluted environment with a high concentration of 1% in terms of atmospheric pressure, and causes a problem of contamination. Therefore, this method cannot be used in the processing of a semiconductor requiring a high pressure environment as described above. is there.

The present invention has been made in view of the above circumstances, and is intended to reduce the time in a cooling / decompression process when a semiconductor is subjected to gas processing at a high temperature and a high pressure. It is an object of the present invention to provide a high-temperature high-pressure gas processing method capable of increasing a processing rate in processing.

[0008]

According to the present invention, the following technical measures have been taken in order to achieve the above object. That is, the high-temperature and high-pressure gas processing method according to the present invention includes, as an overall flow, a heating and pressurizing step, a holding step, and a cooling and depressurizing step performed on a workpiece loaded into a processing chamber in a pressure vessel. In the cooling / decompression step, cooling is first performed to stop heating while maintaining the high pressure state at the end of the holding step. The procedure is such that pressure reduction is started when the temperature and the predetermined pressure are reached.

When the pressure in the processing chamber is reduced to the atmospheric pressure due to the above-described reduced pressure, the object to be processed in the processing chamber is set to the desired handling temperature. . After all, in the present invention, from the end of the holding step, cooling at a high cooling rate is performed for a predetermined time using the good heat radiation property of the gas in a high temperature environment, so that the temperature drop of a predetermined width is early. Then, pressure reduction is started before the temperature of the processing chamber becomes too low. In this pressure reduction process, a reduction in gas density, that is, a temperature reduction caused by adiabatic expansion due to an increase in gas volume is effectively and sufficiently performed. The temperature of the gas in the vicinity of the object to be processed is rapidly cooled by utilizing the temperature and preventing the gas from excessively acting.

Here, the term "handling temperature" refers to a temperature at which an object to be processed can be handled at room temperature by a direct or indirect manual operation or a robot operation. It is preferred that The most important thing in performing the above steps is when to start depressurization,
It is determined as follows. The temperature drop of the processing chamber and the object to be processed which occurs when the pressure reduction is not started, that is, when only the heating is stopped under the high pressure environment (hereinafter, a curve indicating the temperature drop is referred to as a “high pressure cooling curve”) is It can be determined almost unambiguously mainly by the initial temperature of the processing chamber and the object to be processed and the internal volume of the processing chamber.

[0011] Further, regarding the temperature drop of the processing chamber and the object to be processed which occurs when the heating is stopped and the pressure is reduced at the same time (hereinafter, a curve indicating the temperature drop is referred to as a "cooling curve under reduced pressure"). In addition, the heat capacity of the object, the gas used, and the structure of the processing chamber, the internal volume of the processing chamber, the type of the object and the gas used, the temperature and the pressure of the processing chamber and the object to be processed are approximately unique. Is required. Therefore, for each of the cooling curve under high pressure and the cooling curve under reduced pressure, after performing a plurality of tests in advance when the various thermal conditions as described above are changed, the individual test results are used as data. Accumulate.

First, when the pressure in the processing chamber becomes atmospheric pressure (when the processed object is taken out of the pressure vessel), a desired handling temperature for the object is determined. Next, a cooling curve under reduced pressure in which the handling temperature is drawn as a target value on the low temperature side is selected from the accumulated data. Further, a high-pressure cooling curve drawn with the temperature and pressure of the processing chamber at the end of the holding step as conditions on the high-temperature high-pressure side is selected from the accumulated data.

When the handling temperature, the cooling curve under high pressure, and the cooling curve under reduced pressure are obtained in this way, the decompression as a point of intersection between the low temperature side of the high pressure cooling curve and the high temperature side of the reduced pressure cooling curve is performed. The start time can be determined. When a casing made of an airtight material is provided in the processing chamber of the pressure vessel in a state where the casing can surround the workpiece, the casing functions as a barrier for suppressing heat from flowing into and out of the workpiece. Further, it is possible to limit the use of cooling due to the change in enthalpy due to the reduced pressure to the casing and the object to be processed, and it is possible to increase the efficiency.

In addition, the casing can prevent natural gas (such as gas impurity components) from directly reaching the object to be processed by riding on natural convection based on the temperature difference, or can have a heat insulating structure provided inside the pressure vessel. It is possible to prevent dust generated from a body, a heater, or the like from adhering to an object to be processed. In this case, if the temperature measuring means is provided inside the casing, the temperature in the processing chamber can be accurately detected.Therefore, if the temperature measurement at the start of the decompression is performed by the temperature measuring means, the heater can be used. There is also obtained an advantage that the temperature can be accurately controlled and the inside of the processing chamber can be easily controlled to a predetermined temperature.

As a result, a high-quality and uniform-quality semiconductor can be obtained as a processed semiconductor.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a pressure processing apparatus 1 suitably used for carrying out the high-temperature and high-pressure gas processing method according to the present invention. The pressure processing apparatus 1 has a cylindrical pressure vessel 4 having an upper lid 2 and a lower lid 3, and a press frame (not shown) for gripping the pressure vessel 4 in the axial direction (up and down). A gas supply / discharge device (not shown) capable of supplying and discharging an inert gas such as argon gas or nitrogen is connected to the pressure vessel 4 via a gas passage 5 provided in the upper lid 2 and the like. A vacuum pump (not shown) is connected via an air passage 6 provided in the upper lid 2 and the like.

A heat insulating structure 7 having an inverted cup shape is provided in the pressure vessel 4, and a processing chamber 8 is formed inside the heat insulating structure 7. On the lower side of the processing chamber 8, a base 10 is provided so as to be mounted on the lower lid 3.
Heaters 11 and 12 which are divided into upper and lower stages along the inner surface of the heat insulating structure 7 are provided. The upper and lower heaters 11 and 12 are of a resistance wire heating type and are separately wired so that independent temperature control is possible.

A support device 15 of a multi-stage support system is provided on the base 10 via a getter member 14 made of Ti, Zr or the like, which can support a plurality of workpieces W up and down. Accordingly, the above-described heaters 11 and 12 are in a state of surrounding the support device 15. The number of supports of the workpiece W in the support device 15 is preferably equal to the number of lots of the workpiece W (for example, one lot is 13 or 25) or a multiple thereof. .

The supporting device 15 and the heaters 11 and 12
A casing 16 having an inverted cup shape is provided between the two.
5 is the form to be surrounded. This casing 1
Numeral 6 is made of an air-tight material, which can prevent gas impurity components and the like contained in the inert gas from directly contacting the workpiece W supported by the support device 15 and a heat insulating structure. 7 and the dust generated from the heaters 11 and 12 can be prevented from reaching the workpiece W. A gap 17 is provided at a lower end portion of the casing 16, and the gap 17 serves to protect the casing 16 by eliminating a pressure difference between the inside and the outside of the casing 16.

A support device 15 is provided inside the casing 16.
A temperature measuring means 18 is provided at a position corresponding to the uppermost processing object W, and the temperature of the upper heater 11 can be controlled by the temperature measuring means 18. A temperature measuring means 19 is provided at a position corresponding to W, and the temperature of the lower heater 12 can be controlled by the temperature measuring means 19. Since the temperature measuring means 18 and 19 are provided inside the casing 16, the temperature distribution in the casing 16 can be directly detected, and an accurate detection result can be obtained. Since proper control can be performed, the entire area in the casing 16 can be soaked.

Using the pressure processing apparatus 1 having such a configuration,
In order to perform the high-temperature and high-pressure gas processing according to the present invention on a semiconductor such as a silicon wafer, first, the pressure vessel 4 is opened, and a plurality of (for example, two lots)
Is supported. And this support device 15
Pressure casing 4 by covering casing 16 from above.
Are assembled as shown in FIG. Then, as shown in FIG. 1, the heating / pressurizing step, the holding step, and the cooling / depressurizing step are sequentially performed in this order.

In the heating / pressurizing step, first, a vacuum pump (not shown) is operated to evacuate the processing chamber 8 of the pressure vessel 4, and then a gas supply / discharge device (not shown) is operated to operate the processing chamber. 8
Is filled with an inert gas such as an argon gas or a nitrogen gas, and is pressurized to a predetermined internal pressure (here, 150 MPa) over a predetermined time. During the same time, the heating by the heaters 11 and 12 is started, and the processing chamber 8 is heated to a predetermined temperature (7 in this case).
00 ° C). In the next holding step, the detected temperature is monitored by the upper and lower temperature measuring means 18 and 19, and the electric power applied to the heaters 11 and 12 is controlled as necessary. The temperature and the internal pressure are maintained for a predetermined time while maintaining the uniformity of all the workpieces W.

In the next cooling / depressurizing step, the heating is stopped by cutting off the power supplied to each of the heaters 11 and 12 without depressurizing, that is, while maintaining the high pressure state at the end of the holding step. Cooling is performed, and then pressure reduction is started when the temperature of the processing chamber 8 reaches a predetermined temperature and a predetermined pressure by the cooling. With this reduced pressure, the processing object W is set to the desired handling temperature just when the processing chamber 8 becomes atmospheric pressure. Here, the curve indicating the temperature drop that occurs from the end of the holding step to the start of depressurization is referred to as a “high-pressure cooling curve”, and the curve indicating the temperature drop that occurs from the start of depressurization until the pressure reaches atmospheric pressure is referred to as “depressurization”. A method for determining the pressure reduction start timing will be described as a “lower cooling curve”.

First, a desired handling temperature is determined. The handling temperature is a temperature at which the processed object W can be handled at room temperature by a direct or indirect manual operation or a robot operation, and is preferably 20 ° C or more and 100 ° C or less. Next, from a plurality of data accumulated as a cooling curve under reduced pressure (that is, a material storing a plurality of test results actually performed in the past), as a rule of thumb, the target temperature after cooling is set to the above-mentioned handling temperature. Select a cooling curve under reduced pressure that is suitable. The individual cooling curve under reduced pressure in the accumulated data is represented by the internal volume of the processing chamber 8,
The volume and material of the workpiece W, the type of gas used, the workpiece W and the gas used, and also the internal structure of the processing chamber 8 (for example, the casing 16, the support device 15, the base 10, the heat insulating structure 7)
, Etc.), and various thermal conditions such as the temperature and pressure of the processing chamber 8.

From a plurality of data accumulated as a cooling curve under high pressure (that is, a material storing a plurality of test results actually performed in the past), as an empirical rule, the temperature at the time of starting the cooling is calculated as follows. A high pressure cooling curve that matches the temperature of the processing chamber 8 at the end of the holding step is selected. The individual high-pressure cooling curves in the accumulated data are obtained by making the internal volume of the processing chamber 8 and various thermal conditions such as temperature and pressure at the start of cooling different.

If the handling temperature, the cooling curve under reduced pressure, and the cooling curve under high pressure are sequentially determined in this way, the intersection of the high-temperature side area of the cooling curve under reduced pressure and the low-temperature side area of the cooling curve under high pressure is naturally determined as follows: It is possible to determine the start time of the decompression. After the cooling and depressurizing steps determined as described above, one cycle of the high-temperature and high-pressure gas processing is performed by opening the pressure vessel 4 and normally taking out the processed object W (semiconductor) from the supporting device 15. Will end. FIG. 3 shows the mechanism of the temperature decrease that occurs in the processing chamber 8 after the start of the depressurization, using a TS diagram (Mollier diagram) of the pressure medium gas.

In FIG. 3, point A is a state in which the temperature is lowered to 500 ° C. in a high-pressure environment with a high cooling rate from the stage when the temperature is reduced to 700 ° C. and 150 MPa after the completion of the holding step. . Thereafter, when the gas in the processing chamber 8 is released over 10 to 20 minutes and the pressure is reduced from the atmospheric pressure to 1 MPa, the gas temperature should be point B on the TS diagram due to adiabatic expansion (change of isentropy). . Therefore, at this time, the enthalpy of the gas theoretically decreases from H1 at the point A to H2 at the point B and absorbs the heat of H1-H2. Each of them has a heat capacity, and due to these heat dissipation phenomena, the position does not reach the position shown at -180 ° C, but settles at a point C (room temperature to 100 ° C) near room temperature.

Assuming that the enthalpy of the point C is H3,
Actually, the enthalpy change due to the reduced pressure that has contributed to the removal by the reduced pressure is H1−H3, and the temperature of the workpiece W is controlled according to a desired position by skillfully utilizing the enthalpy change. Is what makes it possible. It should be noted that the workpiece W is
Since the casing 16 is housed in the casing 16, the casing 16 acts as a barrier that also suppresses heat inflow and outflow. The use of the cooling by the enthalpy change due to the decompression reduces the casing 16, the workpiece W in the casing 16, and a boat that receives the same. It is possible to limit to jigs such as (not shown), and it is possible to increase efficiency.

If measures such as using quartz excellent in heat insulation for the casing 16 or forming the casing 16 into a double structure are taken, it is more preferable, and it is possible to further utilize the temperature decrease due to the reduced pressure. Become.

[0030]

FIG. 4 shows two specific embodiments (X, Y) relating to the cooling and depressurizing steps when the present invention is employed. X in FIG. 4 indicates a case where the processing chamber 8 is at 430 ° C. and 170 MPa at the end of the holding process, and the handling temperature of the processing target W at the time when the pressure reaches atmospheric pressure is 56 ° C. This is the case when it is decided to do so. In this case, the decompression start timing is as follows.
It took 20 minutes from the end of the holding step to the start of the pressure reduction. The pressure reduction time required from the start of the pressure reduction to the atmospheric pressure was 20 minutes.

Further, Y in FIG. 4 indicates the case where the processing chamber 8 is at 400 ° C. and 170 MPa at the end of the holding step and at the time when the atmospheric pressure is reached. This is the case where the handling temperature is determined to be 81 ° C. In this case, when the pressure in the processing chamber 8 is 35
It was at 3 ° C. and 153 MPa, and it took 15 minutes from the end of the holding step to the start of this pressure reduction. Also,
The pressure reduction time required from the start of the pressure reduction to the atmospheric pressure was 25 minutes. In addition, in this Y, an experiment was performed to lower the handling temperature of the workpiece W from 81 ° C. to 50 ° C. or less, and it took an additional hour. Therefore, it means that the entire processing time is extended by one hour as compared with X. However, even if the temperature of the processing object W is still 81 ° C., if the robot hand or the like is used, it is taken out from the pressure vessel 4 or thereafter. Can be handled, and the above-mentioned one hour extension is not necessarily required.

On the contrary, if the start of the depressurization is set to be earlier than 15 minutes, for example, if the start of the decompression is set to be earlier than 15 minutes, the temperature will exceed 100 ° C. even at the time of the atmospheric pressure. 15 to start decompression
If it is later than minutes, the pressure of the workpiece W becomes equal to or lower than 0 ° C. when the atmospheric pressure is reached, and water droplets are generated on the surface of the workpiece W when the workpiece W is taken out of the pressure vessel 4 as it is. Will be disabled. As a result, in both the case of X and the case of Y, the total processing time required for the cooling / depressurizing step is extremely short, for example, 40 minutes. One cycle of high-temperature and high-pressure gas processing can be performed in about 1 hour to 3 hours, and continuous processing can be performed a large number of times, such as 5 to 20 times a day, so that the semiconductor processing rate can be increased.

Table 1 shows that when the present invention is implemented in processing 50 8-inch wafers (A), when the pressure reduction is started simultaneously with the end of the holding step (B), and after the holding step is completed. It shows the result of comparison with the case (C) in which the high pressure state is maintained until the temperature reaches 200 ° C. and then the pressure reduction is started.
B is similar to the method previously described in FIG.
Can be said to be similar to the method described with reference to FIG.

[0034]

[Table 1]

As is clear from Table 1, it can be seen that the entire processing time can be remarkably reduced by implementing the present invention. In the case of C, since the temperature of the workpiece W when the pressure was reduced to the atmospheric pressure was lower than 0 ° C., the heater was further heated, and the heating was performed until the temperature of the workpiece W reached about 30 ° C. I'm taking out from. By the way, the present invention is not limited to the above-described embodiment, and various changes and the like according to the embodiment can be made on the detailed procedure and the configuration of the pressure processing apparatus 1 to be used.

[0036]

As is clear from the above description, in the high-temperature and high-pressure gas processing method according to the present invention, in the cooling / decompression step, the cooling is performed by stopping the heating while maintaining the high pressure state at the end of the holding step. When the processing chamber reaches atmospheric pressure by performing a procedure such that pressure reduction is started when the processing chamber reaches a predetermined temperature and a predetermined pressure by allowing it to cool, when the processing chamber reaches atmospheric pressure, The product has just been brought to the desired handling temperature, which can significantly reduce the time required for the cooling / decompression process, thereby dramatically increasing the processing rate of high-quality semiconductors in high-temperature, high-pressure gas processing. Things.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between temperature and pressure over time in a high-temperature and high-pressure gas processing method according to the present invention.

FIG. 2 is a cross-sectional view showing a pressure processing apparatus suitably used for performing a high-temperature and high-pressure gas processing method according to the present invention.

FIG. 3 is a TS diagram (Mollier diagram) illustrating a mechanism of temperature decrease after the start of pressure reduction.

FIG. 4 is a line graph showing two experimental examples of a cooling / decompression step employing the method of the present invention.

FIG. 5 is a diagram showing the relationship between temperature and pressure over time in a conventional high-temperature and high-pressure gas processing method.

FIG. 6 is a diagram showing the relationship between temperature and pressure over time in another conventional high-temperature and high-pressure gas processing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pressure processing apparatus 4 Pressure vessel 8 Processing chamber 16 Casing 18 Temperature measurement means 19 Temperature measurement means W Workpiece

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tsuneharu Masuda 2-3-1 Shinhama, Araimachi, Takasago City, Hyogo Prefecture Inside Kobe Steel, Ltd. Takasago Works (72) Inventor Makoto Kadoguchi 2-3, Araimachi Shinama, Takasago-shi, Hyogo Prefecture No. 1 Inside Kobe Steel, Ltd. Takasago Works

Claims (5)

[Claims] An object (W) loaded in a processing chamber (8) in a pressure vessel (4) is subjected to a heating / pressurizing step, a holding step, and a cooling / depressurizing step, and is taken out of the vessel. In the gas treatment method, in the cooling / depressurizing step, cooling is stopped first while stopping the heating while maintaining the high pressure state at the end of the holding step, and then, after the cooling, the processing chamber is set to a predetermined temperature and a predetermined pressure. A high-temperature and high-pressure gas processing method characterized in that a pressure is started at the stage when the pressure is reduced, so that an object to be processed or a desired handling temperature is simultaneously obtained at the stage when the pressure is reduced to the atmospheric pressure. 2. The start timing of pressure reduction is determined by an empirical rule from the above-mentioned handling temperature and various thermal conditions including the heat capacity of the workpiece (W) on the assumption that the handling temperature is set to a target value. 2. The high-temperature and high-pressure gas processing method according to claim 1, wherein the prediction is performed based on a cooling curve under reduced pressure and a cooling curve under high pressure obtained from the end of the holding step. 3. The method according to claim 1, wherein the handling temperature is not lower than 20 ° C.
3. The method according to claim 1, wherein the temperature is 0 ° C. or less.
The high-temperature and high-pressure gas processing method according to the above. 4. A casing (16) made of an airtight material is provided in the pressure vessel (4) so as to surround the workpiece (W). The high-temperature and high-pressure gas processing method according to any one of the above. 5. A temperature measuring means (18, 19) is provided in said casing (16), and said temperature measuring means (18, 1) is provided.
5. The high-temperature and high-pressure gas processing method according to claim 4, wherein the temperature at the start of the pressure reduction is detected according to 9).