JP3184666B2 - Operating method of plasma device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma apparatus and, more particularly, to a method for removing moisture trapped on a susceptor surface on which an object to be processed is placed.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor processing apparatus,
In order to obtain a vertical pattern shape and a high selectivity, a low-temperature processing method for lowering the temperature of a reaction surface of an object to be processed, for example, a semiconductor wafer, is known. In such low-temperature processing, it is important to accurately maintain the temperature of the reaction surface of the object within the allowable processing temperature range in order to improve the product yield and perform fine surface processing. In particular, recently, as the reaction surface temperature of the object to be processed is controlled to a lower temperature, the processing accuracy of the product is improved.

[0003] Therefore, conventionally, a coolant is sent from a cooling circuit into a susceptor (or a lower electrode) on which an object is placed, and the susceptor is cooled to an extremely low temperature area. There is known a technique for cooling down.

However, when the susceptor is cooled to an ultra-low temperature range, for example, a temperature of -100 ° C. or less, in an atmospheric atmosphere or a pressure atmosphere of the order of 10 ⁻³ Torr, moisture is trapped on the surface of the susceptor due to a high partial pressure of water. The moisture has had an adverse effect on the object to be processed during the plasma processing or has caused corrosion of the apparatus, and thus a solution has been sought.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to cool a susceptor to a very low temperature range in a high vacuum atmosphere. Another object of the present invention is to provide a new and improved method of operating a plasma apparatus , which can minimize moisture trapped on a susceptor surface.

Another object of the present invention is to easily remove trapped moisture even when moisture is trapped on the surface of a susceptor cooled to a very low temperature range in a high vacuum atmosphere. A new and improved method of operating a plasma device is provided. Still another object of the present invention is to reduce the time required for a target object introduced into a processing chamber to be cooled to a target temperature when performing low-temperature plasma processing, thereby improving the throughput of the low-temperature plasma processing. It is an object of the present invention to provide a new and improved method of operating a plasma device which can be operated .

[0007]

According to a first aspect of the present invention, a processing chamber for performing plasma processing, and the processing chamber are provided.
A susceptor that is placed inside the
Heating means and cooling means provided in the septum, and the treatment
Plasma provided with exhaust means for evacuating the room
In the apparatus, the pressure in the processing chamber is controlled by the exhaust means.
After reducing the pressure to the processing pressure, the cooling means and the heating
Means and a switching means in a predetermined cycle to switch the susceptor.
Set the temperature to the target temperature while raising or lowering the water dew point
A method for operating a plasma device is provided, characterized in that the method comprises:

Furthermore, for example, as in the invention of claim 2, the transport arm unloaded from the processing chamber is transported into the processing chamber to be processed, may be provided with cooling means.

[0009]

SUMMARY OF According to claim 1, the process chamber process pressure, after a high vacuum state, for example, 10 -3 ^Torr or less, the
While raising and lowering the temperature of the susceptor around the dew point of water
Since the target temperature is reached, for example, equipment maintenance
Increases when the processing chamber is returned to atmosphere
Exhaust water before the susceptor starts cooling.
And the temperature of the susceptor drops below the dew point of water.
Moisture trapped on the susceptor surface when lowered
The temperature of the susceptor rose above the dew point temperature of water.
Sometimes it is possible to evaporate and exhaust. as a result,
In particular, it is trapped on the susceptor surface after the above maintenance.
Drastically reduces the effect of water on plasma processing.
Improve product yields as they can be kept to a minimum
Can be done.

Further, according to the invention described in claim 2 ,
Since the workpiece held by the transport arm can be transported while being cooled, for example, the precooled workpiece is prevented from warming up during transport, and the workpiece is loaded into the processing chamber in the precooled state. It becomes possible.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The operation of a plasma apparatus according to the present invention will be described below.
The method will be described in detail with reference to the accompanying drawings. 1 and 2 show a multi-chamber type plasma apparatus to which the present invention can be applied. However, it is needless to say that the present invention is not limited to a multi-chamber type plasma apparatus as shown in the figure, but can be applied to various plasma apparatuses capable of performing ultra-low temperature processing.

As shown in FIG. 1, a multi-chamber plasma apparatus 1 to which the method of the present invention can be applied includes a load lock chamber 3 in which a transfer arm 2 is installed, a first processing chamber 4,
The second processing chamber 5, the third processing chamber 6, the first cassette chamber 7, and the second cassette chamber 8 are respectively provided with gate valves 9, 10,
11, 12, and 13 are arranged. Furthermore, the first and second cassette chambers 7 and 8 communicate with the atmosphere via gate valves 14 and 15, respectively.

FIG. 2 shows the plasma apparatus 1 shown in FIG.
It is the schematic sectional drawing cut | disconnected by the A line. As illustrated, the processing chamber 4 is an airtight chamber surrounded by, for example, an aluminum wall, and an upper electrode 16 is disposed above the processing chamber 4. A processing gas flow passage is provided inside the upper electrode 16,
A processing gas, for example, a CF ₄ gas supplied from a gas source 17 via a mass flow controller (not shown) is blown into the processing chamber from a plurality of holes 19 opened on the lower surface of the upper electrode 16.

Below the processing chamber 4, a susceptor 20 on which a semiconductor wafer W to be processed is placed is installed. The susceptor 20 is connected to a high-frequency power supply 21 and also functions as a lower electrode for generating plasma in the processing chamber. Inside the susceptor 20, a cooling means 24 connected to a heating means 22 and a cooling circuit 23 is provided. These heating means 22 and cooling means 24 are configured to be capable of on / off control in accordance with a signal from a controller (not shown).

An exhaust pipe 26 is provided near the bottom of the processing chamber 4. The exhaust pipe 26 is provided with valve means 27 and 2
The processing chamber 4 is evacuated by receiving a signal from a controller (not shown). Further, a gate valve 9 is provided on one wall surface of the processing chamber 4, and by opening and closing the gate valve 9, the processing chamber 4 and the load lock chamber 3 communicate with each other, for example, at the time of loading / unloading operation of an object to be processed. It is possible.

At the center of the load lock chamber 3, a transfer arm 2 having a telescopic arm is installed. A cooling means 31 connected to the cooling circuit 23 is provided in the mounting table 30 of the transfer arm 2, and the transfer arm 2 and the transfer arm 2 are gripped by a signal from a controller (not shown). The object to be processed is configured to be cooled.

A heating means 32, for example, a heating lamp, is disposed above the load lock chamber 3, and is turned on in response to a signal from a controller (not shown). The object to be processed gripped by 2 is configured to be heated. In the illustrated example, a heating lamp is used as the heating means 32. However, as described later, the transfer arm 2 is heated as desired by blowing high-temperature nitrogen gas or using a heating means built in the transfer arm itself. Such a configuration is also possible.

An exhaust pipe 3 is provided at the bottom of the load lock chamber 3.
3 are installed. The exhaust pipe 33 communicates with the vacuum pump 29 via the valve means 34 and the valve means 28,
The inside of the load lock chamber 3 can be evacuated as required. A gate valve 13 is provided on a part of the wall of the load lock chamber 3. By opening and closing the gate valve 13, the cassette chamber 7 and the load lock chamber 3 can communicate with each other when the semiconductor wafer W is loaded and unloaded. It is configured to be able to.

In the center of the cassette chamber 7, a wafer cassette 36 mounted on a mounting table 35 is installed.
In the wafer cassette 36, a plurality of semiconductor wafers W
Can be stored, and a predetermined semiconductor wafer W can be taken out by the transfer arm 2 as needed. Cooling means 37 communicating with the cooling circuit 23 is also provided inside the mounting table 35, and cools the mounting table 35, the wafer cassette 36, and the semiconductor wafer W according to a signal from a controller. It is possible.

In the upper part of the cassette chamber 7, a heating means 38, for example, a high-temperature nitrogen outlet is provided. The high-temperature nitrogen blowing port 38 communicates with a high-temperature nitrogen source 39, and blows high-temperature nitrogen into the cassette chamber 7 in response to a signal from a controller (not shown).
6 or the semiconductor wafer W can be heated.
Further, an exhaust pipe 40 is provided at the bottom of the cassette chamber 7. The exhaust pipe 40 is provided with valve means 41 and valve means 2
The vacuum chamber 29 communicates with a vacuum pump 29 through the vacuum chamber 8 so that the inside of the cassette chamber 7 can be evacuated as necessary. Further, a gate valve 14 is provided on one wall of the cassette chamber 7, and by opening and closing the gate valve 14, the cassette chamber 7 and the atmosphere can be communicated with each other. It is possible to carry in and out.

The configuration of the multi-chamber type plasma apparatus 1 to which the present invention can be applied has been described. Next, the operation of the plasma device 1 will be described. First, at the time of processing, the gate valve 14 for communicating the atmosphere with the cassette chamber 7 is opened, and the wafer cassette 36 containing, for example, 25 semiconductor wafers W to be processed is transferred to the cassette cassette by a transfer robot (not shown). Mounting table 3 in room 7
5 and the gate valve 14 is closed.
The cassette chamber 7 is evacuated to a vacuum atmosphere, for example, 10 ⁻¹ Torr by the vacuum pump 23 via an exhaust pipe 40 connected to the cassette chamber 7.

During this time, an appropriate refrigerant is sent from the cooling circuit 23 to the cooling means 35 in the cassette mounting table 35, thereby cooling the mounting table 35 itself. The placed wafer cassette 36 and the semiconductor wafers W stored in the wafer cassette 36 are cooled to a predetermined temperature, for example, -50 ° C to -80 ° C.
Can be cooled beforehand.

That is, when the low-temperature plasma processing is performed, it takes time to cool the semiconductor wafer W at room temperature to a predetermined temperature even if the semiconductor wafer W is brought into the processing chamber, which may deteriorate the throughput. is there. In order to avoid such a situation, according to this embodiment, the semiconductor wafer W is previously stored in the cassette chamber 7 by, for example, -50.
By cooling the semiconductor wafer W to a temperature of about −80 ° C. to −80 ° C., it is possible to shorten the time for cooling the semiconductor wafer W introduced into the processing chamber to the target temperature, and as a result, the throughput of the low-temperature plasma processing can be reduced. Can be improved.

In this embodiment, the pre-processing for cooling the semiconductor wafer W is executed in the cassette chamber 7, but what is important is that the object to be processed is carried into the processing chamber 4. Temperature to some extent, for example -5
It is pre-cooled to 0 ° C. to −80 ° C. Therefore, a separate pre-cooling chamber is provided, the object to be processed is temporarily stored in the pre-cooling chamber, and after being pre-cooled, it is carried into the processing chamber 4. It is also possible to configure so that Alternatively, a section for pre-cooling the object to be processed may be provided in the load lock chamber 3, and the object to be processed may be pre-cooled in the section and then loaded into the processing chamber 4.

Next, the gate valve 13 between the load lock chamber 3 and the cassette chamber 7 is opened, and the object W is placed in the cassette chamber 7 by the transfer arm 2. The gate valve 13 is taken out, held and transported into the load lock chamber 3, and the gate valve 13 is closed. The exhaust pipe provided in the load lock chamber 3 is opened, and the load lock chamber 3 is evacuated to a vacuum atmosphere, for example, 10 ⁻³ Torr by the vacuum pump 29.

In the meantime, according to the illustrated embodiment, an appropriate refrigerant is sent from the cooling circuit 23 to the cooling means 31 in the transfer arm mounting table 30, and the transfer arm 2 itself is cooled by the heat transfer. It is possible. As a result, it is possible to prevent the object W pre-cooled in the cassette chamber 7 from being heated by the heat from the transfer arm 2 during transfer, and can be carried into the processing chamber 4 in a pre-cooled state. Become.

Next, the gate valve 9 between the load lock chamber 3 and the processing chamber 4 is opened, and the workpiece W pre-cooled by the transfer arm 2 in a cooled state is placed in the processing chamber 4. And is mounted and fixed on the susceptor 20 by a fixing means (not shown), for example, an electrostatic chuck, the gate valve 9 is closed, and the inside of the processing chamber 4 is set to a desired pressure atmosphere through the exhaust pipe 26. The pressure is reduced to However, the susceptor on which the object to be processed W is placed needs to be cooled to an ultra-low temperature range in advance.

Here, initially, for example, the device
<br/> when returning the processing chamber 4 by the practice of such the atmosphere Maintenance Manual is the susceptor 20 which is at room temperature or higher temperatures like bears, subatmospheric pressure atmosphere 10 -3 ^Torr in the above example When the temperature is lowered to a very low temperature range, for example, a temperature of -100 ° C. or lower, the partial pressure of the water contained in the processing chamber 4 is high, so that the water is trapped on the surface of the susceptor.
During the plasma processing, the object to be processed may be adversely affected, or the apparatus may be corroded. Therefore, it is necessary to minimize the amount of moisture trapped on the surface of the susceptor during cooling. Therefore, according to the method of the present invention, the cooling of the susceptor 20 is started after the pressure in the processing chamber 4 is reduced to 10 ⁻³ Torr or less. As a result, according to the present invention, since the moisture contained in the processing chamber 4 is exhausted before the start of cooling, even when the susceptor 20 is cooled to an extremely low temperature range, the moisture adhering to the surface of the susceptor 20 is cooled. Can be minimized.

In order to prevent moisture from adhering to the susceptor placed in an ultra-low temperature atmosphere of -100 ° C. or lower, the lower the pressure atmosphere in the processing chamber 4 is, the better the effect is obtained. In particular, it is more preferable to set the target ultimate pressure of the processing chamber 4 to 10 ^-5 Torr or less.

Even when the moisture adhering to the susceptor is minimized as described above, it is necessary to remove the residual moisture because the very small amount of moisture is trapped on the susceptor surface. This water removing method will be described with reference to FIG. According to the method of the present invention, for example, 10 ^-3
The susceptor placed in an ultra-low temperature atmosphere of -100 ° C. or less under a high vacuum of Torr or less
The heating and cooling cycle is repeated by switching on and off of the cooling means 24 and the cooling means 24, and the temperature of the susceptor fluctuates up and down with the dew point temperature of water as a boundary.

As shown in FIG. 3, under a high vacuum of 10 ⁻³ Torr or less, the susceptor temperature is, for example, −90 ° C.
By oscillating between 140 ° C., the water trapped at −140 ° C. can be evaporated and exhausted at −90 ° C. By repeating this operation for several cycles, the water adheres to the susceptor. The removed water can be completely removed.

According to the method of the present invention, in the cooling process of the susceptor, the susceptor functions as a kind of cryopanel by repeatedly heating and cooling the temperature of the susceptor up and down at the boundary of the dew point of moisture. It is possible to effectively dehumidify the processing chamber by repeating the trapping of water and the evaporative exhaust.

After the preparation for the ultra-low temperature plasma processing is completed through the above steps, the processing gas is supplied to the processing gas source 17.
It is introduced into the processing chamber 4 from the upper electrode 18 via a mass flow controller (not shown). Then
High-frequency power is supplied from the high-frequency power supply 21 to the lower electrode via a matching device (not shown), and plasma etching of the processing target W is started.

When the desired plasma etching process is completed, the high-frequency power supply 21 is stopped to stop the generation of plasma and the supply of the processing gas. further,
In order to replace the processing gas and the reaction product in the processing chamber 4, an inert gas such as nitrogen is introduced into the processing chamber 4, and the gas is evacuated by the vacuum pump 29.

After the residual processing gas and reaction products in the processing chamber 4 are sufficiently exhausted, the gate valve 9 provided on the side surface of the processing chamber 4 is opened, and the load lock chamber 3 adjacent to the gate valve 9 is opened. The transfer arm 2 moves to the position of the processing target W in the processing chamber 4, holds the processing target W, transfers the processing target W into the load lock chamber 3, and closes the gate valve 9. Subsequently, when the subsequent processing is performed in the second processing chamber 5 or the third processing chamber 6, the workpiece W is loaded into each processing chamber. Here, all the processing ends. An operation process of returning the workpiece W to the cassette chamber 7 and then carrying it out to the atmosphere will be described.

As described above, since the object to be processed W is processed at an extremely low temperature, if the object to be processed W in a cooled state is carried out to the atmosphere as it is, dew condensation may occur. Measures are needed. In the illustrated embodiment, a heating means 32, for example, a heating lamp, is provided above the load lock chamber 3, so that the semiconductor wafer W held by the transfer arm 2 can be raised to room temperature or higher. Alternatively, as shown in the above embodiment, a heating means 38, for example, a high-temperature nitrogen blow-off port is provided above the cassette chamber 7, and the semiconductor wafer W stored in the wafer cassette 36 is heated to a room temperature or higher by high-temperature nitrogen. It is possible to raise.

As described above, the semiconductor wafer W is raised to room temperature or higher in the load lock chamber 3 or the cassette chamber 7 and then carried out to the atmosphere, thereby effectively preventing the occurrence of dew condensation. In the above-described embodiment, the temperature of the processing target W is increased in the load lock chamber 3 or the cassette chamber 7, but a separate temperature raising chamber (not shown) is provided. It is also possible to adopt a configuration in which the control is performed.

Further, when all processes are completed and maintenance is performed, if the susceptor under vacuum at a temperature of -100 ° C. or lower is returned to the atmosphere as it is, moisture may condense. Therefore, in the illustrated embodiment, it is preferable that the susceptor is heated to a room temperature or higher by the heating means 22 before returning to the atmosphere. The above is the description of the operation of the embodiment in which the method of the present invention is applied to a multi-chamber type plasma etching apparatus.

In this specification, an example in which the plasma apparatus according to the present invention is applied to an etching apparatus has been described. However, the plasma apparatus according to the present invention is not limited to the above-described example, but includes an ashing apparatus, a sputtering apparatus, and an ion implantation apparatus. ,
The present invention can be applied to a plasma CVD apparatus or the like.

As described above, according to the method of the present invention, even when the susceptor is cooled to a very low temperature range in a high vacuum atmosphere, the amount of water trapped on the susceptor surface is minimized. It is possible to suppress. Also book
According to the method of the invention, cooling to ultra-low temperature range in high vacuum atmosphere
Even if moisture traps on the susceptor surface
The susceptor temperature at the dew point
Repeat the heating and cooling cycle so that the degree goes up and down
Removes water trapped on the susceptor surface
It is possible to

Further, for example, since the pre-cooled object can be carried into the processing chamber while being cooled by the transfer arm, the cooling time of the object in the processing chamber can be shortened, and the throughput can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a multi-chamber type plasma apparatus to which the present invention can be applied.

FIG. 2 is a schematic sectional view of the plasma device shown in FIG. 1 cut along line AA.

FIG. 3 is a graph showing one embodiment of susceptor temperature control according to the method of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 plasma device 2 transfer arm 3 load lock chamber 4 first processing chamber 7 first cassette chamber 9, 13, 14 gate valve 20 susceptor (lower electrode) 22 susceptor heating means 23 cooling circuit 24 susceptor cooling means 26 exhaust pipe 29 vacuum pump Reference Signs List 30 transfer arm table 31 transfer arm cooling means 32 transfer arm heating means 35 wafer cassette table 36 wafer cassette 37 wafer cassette cooling means 38 wafer cassette heating means

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-40227 (JP, A) JP-A-2-214116 (JP, A) JP-A-1-248521 (JP, A) JP-A-61- 240635 (JP, A) JP-A-60-41229 (JP, A)

Claims (2)

(57) [Claims] A processing chamber for performing a plasma processing; a susceptor in the processing chamber, on which an object to be processed can be mounted;
Heating means and cooling means provided in the susceptor,
In a plasma apparatus provided with an exhaust unit for evacuating the processing chamber, after the pressure in the processing chamber is reduced to a processing pressure by the exhaust unit, the cooling unit and the heating unit are cycled in a predetermined cycle. A method for operating a plasma apparatus, comprising: performing a switching operation to raise and lower the temperature of the susceptor to a target temperature while raising and lowering the dew point temperature of water as a boundary. The 2. A conveying arm for unloading the workpiece from the processing chamber is transported into the processing chamber, wherein the cooling means is provided, the plasma apparatus according to claim 1 how to drive.