Patent Application
20170062250
The present application claims priority from Japanese Patent Application No. 2015-164928 filed on Aug. 24, 2015, the content of which is hereby incorporated by reference into this application.
The present invention relates to a vacuum process apparatus and a method of manufacturing a semiconductor device. The present invention particularly relates to a technique effectively applied to time management of an after-purge after a vacuum process.
In an ashing apparatus that is one of vacuum process apparatuses, after an ashing process of a semiconductor wafer is finished, the semiconductor wafer is transferred to a load-lock chamber. Then, the semiconductor wafer is transferred to a front-end module from the load-lock chamber.
Upon passing the semiconductor wafer from the load-lock chamber to the front-end module, the load-lock chamber is opened to the atmosphere. Upon opening to the atmosphere, the load-lock chamber is first purged by, for example, nitrogen (N2) gas, which is called “main purge.”
Then, when the pressure in the load-lock chamber reaches a pre-set pressure or higher, an after-purge is performed. After the after-purge is finished, an atmosphere gate valve is vented (opened) to make the load-lock chamber opened to the atmosphere.
In the technique of venting to the atmosphere in a load-lock chamber described above, when the after-purge is finished, the atmosphere gate valve is opened, so that the load-lock chamber is opened (vented) to the atmosphere. Thus, if the pressure in the load-lock chamber is not increased even after the after-purge for some reason, a large pressure difference is generated between the load-lock chamber and the front-end module.
In such a situation, when the atmosphere gate valve is opened, the pressure difference causes the atmospheric air to flow into the load-lock chamber from the front-end module, and it poses a problem of jumping of an asked semiconductor wafer due to the pressure of the flowed atmospheric air.
Due to the jumping of the semiconductor wafer, the semiconductor wafer may come into contact with a place rack for storing a plurality of semiconductor wafers, and as a result, it may cause breakage of the semiconductor wafer(s).
The above and other preferred aims and novel characteristics of the present invention will be apparent from the description of the present specification and the accompanying drawings.
The typical ones of the inventions disclosed in the present application will be briefly described as follows.
That is, a typical vacuum process apparatus includes a load-lock chamber and a control unit. The load-lock chamber takes in and out a semiconductor wafer to and from a process chamber in which a vacuum process of the semiconductor wafer is performed. The control unit controls a venting process for putting the load-lock chamber in a vacuum state to an atmospheric state in which the load-lock chamber is opened to atmosphere.
The control unit compares a first set pressure value and a differential pressure value that is obtained by subtracting a second pressure value that is a pressure inside the load-lock chamber right after venting to the atmosphere from a first pressure value that is a pressure inside the load-lock chamber right before venting to the atmosphere, and outputs an alarm when the differential pressure value is lower than the first set pressure value.
Particularly, the control unit compares the differential pressure value and a second set pressure value when the differential pressure value is higher than the first set pressure value, and increases a purge time taken for a purge performed before venting to the atmosphere in the load-lock chamber when the differential pressure value is within a range of the second set pressure value.
The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described below.
Failures in manufacturing of semiconductor devices can be reduced.
In the embodiments described below, the invention will be described in a plurality of sections or embodiments when required as a matter of convenience. However, these sections or embodiments are not irrelevant to each other unless otherwise stated, and the one relates to the entire or a part of the other as a modification example, details, or a supplementary explanation thereof.
Also, in the embodiments described below, when referring to the number of elements (including number of pieces, values, amount, range, and the like), the number of the elements is not limited to a specific number unless otherwise stated or except the case where the number is apparently limited to a specific number in principle. The number larger or smaller than the specified number is also applicable.
Furthermore, in the embodiments described below, it goes without saying that the components (including element steps) are not always indispensable unless otherwise stated or except the case where the components are apparently indispensable in principle.
Similarly, in the embodiments described below, when the shape of the components, positional relation thereof, and the like are mentioned, the substantially approximate and similar shapes and the like are included therein unless otherwise stated or except the case where it is conceivable that they are apparently excluded in principle. The same goes for the numerical value and the range described above.
Also, the same components are denoted by the same reference symbols throughout the drawings for describing the embodiments, and a repetitive description thereof is omitted.
<Configuration Example of Ashing Apparatus>
Hereinafter, an embodiment will be described in detail.
The ashing apparatus 10 which is a vacuum process apparatus includes process chambers 11 and 12, a transfer 13, load-lock chambers 14 and 15, the atmospheric transfer chamber 16, load-ports 17 to 19, and an apparatus control unit 30, as illustrated in
The process chambers 11 and 12 which are chambers for processing are vacuum process chambers for, for example, removing a photoresist formed on a semiconductor wafer, that is, an ashing process. The process chambers 11 and 12 are, for example, plasma ashing apparatuses.
At the stage before the process chambers, the transfer 13 is provided. The transfer 13 is a vacuum transfer chamber. A transfer robot 13a is provided inside the transfer 13.
The transfer robot 13a performs transfer of semiconductor wafers between the process chambers 11 and 12 and the load-lock chambers 14 and 15 provided at the previous stage of the transfer 13.
The load-lock chambers 14 and 15 are vacuum chambers for taking in and out semiconductor wafers without allowing the process chambers 11 and 12 to be vented to the atmosphere. At the previous stage of the load-lock chambers 14 and 15, the atmospheric transfer chamber 16 is provided. The atmospheric transfer chamber 16 is also called an enclosure which forms a closed space isolating semiconductor wafers from contaminating sources to make clean environment.
The atmospheric transfer chamber 16 includes a transfer robot 16a. The transfer robot 16a carries semiconductor wafers in the load-lock chambers 14 and 15 and also takes out semiconductor wafers from the load-lock chambers 14 and 15.
At the previous stage of the atmospheric chamber 16, the load-ports 17 to 19 are provided. The load-ports 17 to 19 are interface units for supplying semiconductor wafers to the process chambers 11 and 12.
The load-ports 17 to 19 take the role of loading semiconductor wafers before being subjected to the ashing process, and storing semiconductor wafer after being subjected to the ashing process in a carrier to pass semiconductor wafers to a transfer system.
The apparatus control unit 30 which is a control unit controls operations of the ashing apparatus 10 and also controls a venting process in the load-lock chambers 14 and 15 to be described later. Particularly, in the venting process, the apparatus control unit 30 manages after-purge time.
A vacuum pump 22 is connected to the load-lock chamber 14 via a valve 21 as illustrated in
The atmospheric pressure sensor 31 outputs an atmospheric pressure signal when the pressure inside the load-lock chamber 14 becomes substantially the same as that of the atmospheric pressure. The pressure meter 32 measures the pressure inside the load-lock chamber 14. The atmospheric pressure signal of the atmospheric pressure sensor 31 and a measured value of the pressure measured by the pressure meter 32 are outputted to the apparatus control unit 30.
The vacuum pump 22 draws the vacuum inside the load-lock chamber 14 in combination with the valve 21. Operations of the valve 21 are controlled by the apparatus control unit 30. When the vacuum inside the load-lock chamber 14 is drawn, the valve 21 is set to be in an open state by the apparatus control unit 30. In addition, when venting the inside of the load-lock chamber 14, the valve 21 is set to be in a closed state by the apparatus control unit 30.
In the atmospheric transfer chamber 16, an atmosphere gate valve 16b to be opened upon venting the load-lock chamber 14 is provided. Opening and closing operations of the atmosphere gate valve 16b are controlled by the apparatus control unit 30. Note that, while the load-lock chamber 14 and the atmospheric transfer chamber 16 are illustrated in
<Configuration Example of Apparatus Control Unit>
The apparatus control unit 30 includes, as illustrated in
Note that part or all of the respective processing functions in the venting process described above may be achieved by hardware. Alternatively, hardware and software may be used in combination.
The memory 30b is a memory exemplified by a flash memory used as a working area of the CPU 30c. The CPU 30c is, for example, a central processing unit. The CPU 30c monitors the atmospheric pressure signal of the atmospheric pressure sensor 31 and a measurement result of the inside of the load-lock chamber 14 by the pressure meter 32 and executes the venting process in the load-lock chamber 14 based on the program stored in the storage unit 30a.
The alarm server 33 activates an alarm based on an alarm signal outputted from the CPU 30c. The monitor 34 displays an alarm based on the alarm signal outputted from the CPU 30c.
<Process Example of Venting Process>
Next, a processing function of the venting process by the apparatus control unit 30 will be described with reference to the flowchart of
The venting process is a process of putting the load-lock chamber 14 or the load-lock chamber 15 in an atmospheric state in which the load-lock chamber is opened to the atmosphere from a vacuum state upon taking out a semiconductor wafer after being subjected to the ashing process from the load-lock chamber 14 or 15 by the transfer robot 16a of the atmospheric transfer chamber 16 illustrated in
First, a main purge is started (step S101). In this main purge, the load-lock chamber 14 in a vacuum state is purged by, for example, nitrogen gas or the like. Next, the CPU 30c determines whether or not the main purge is finished (step S102). This determination that the main purge is finished is a process for determining whether or not the main purge of the process of S101 is finished.
In the process of the step S102, it is determined whether or not the pressure inside the load-lock chamber 14 matches a condition previously set by the main purge. When the pressure matches the previously set condition, it is determined that the main purge is finished.
More specifically, the CPU 30c monitors the atmospheric pressure signal outputted from the atmospheric pressure sensor 31 and a measurement result of the pressure meter 32. Then, when an atmospheric pressure signal is outputted or when the measurement result of the pressure meter 32 shows a pressure value equal to or higher than a pressure value that is previously set, the main purge is determined to be finished. Here, the pressure value that is previously set is a pressure value inside the load-lock chamber 14, for example, about 730 Torr.
In the process of step S102, when it is determined that the main purge is finished, the CPU 30c executes an after-purge (step S103). In this after-purge, purging by nitrogen gas is performed for, e.g., about seven seconds after the determination of the finish of main purge.
Here, a time of seven seconds that is the after-purge time in the process of step S103 is set as a standard after-purge time. Note that the flow rate of the nitrogen gas in the after-purge is same as that of the nitrogen gas in the main purge.
When the after-purge is finished, the process goes to a stability process as a stand-by state for a certain time period (step S104). Here, the stability that is a process of the step S104 is a process performed to stabilize the inside of the load-lock chamber 14. In the stability, the stand-by state is kept for, e.g., about five seconds after the finish of the after-purge.
When the stability is finished, the CPU 30c retrieves a pressure value inside the load-lock chamber 14 from the pressure meter 32 (step S105). The pressure value retrieved in the process of the step S105 is stored in, for example, the memory 30b illustrated in
Then, the CPU 30c opens the atmosphere gate valve 16b in
Next, the CPU 30c accesses the memory 30b to read the first pressure value and the second pressure value and obtains a differential pressure value by subtracting the second pressure value from the first pressure value. From a result, whether or not the differential pressure value is lower than −1 kPa (Pascal) that is a set pressure value previously set is determined (step S108). This value of −1 kPa is a first set pressure value.
In the process of the step S108, when the differential pressure value is lower than −1 kPa, the venting is performed in a state in which the pressure inside the load-lock chamber 14 is low. In this situation, it is determined that there is a possibility that jumping of a semiconductor wafer or the like has occurred, and then, an alarm signal is outputted and the ashing process of a semiconductor wafer to be performed next is stopped (step S109).
The alarm server 33 in
In addition, in the process of the step S108, as a result of subtraction, it is determined whether or not the differential pressure value is a pressure value between −1 kPa or more and 0 kPa or less which is the set pressure value previously set (step S110). The value range, between −1 kPa or more and 0 kPa or less, is a second set pressure value.
In the process of the step S110, when the differential pressure value is a pressure value between −1 kPa or more and 0 kPa or less, the CPU 30c determines that the pressure inside the load-lock chamber is not high enough after the after-purge although the possibility of the occurrence of jumping of a semiconductor wafer is low, and thus the CPU 30c increases the after-purge time in the lot to be performed next by a preset time (step S111). The time to be increased is, e.g., about one second.
Therefore, the after-purge time in the lot to be performed next is about eight seconds as one second is added to the standard after-purge time. The time of “+1 second” increased in the process of the step S111 is stored in the memory 30b.
In addition, in the process of the step S110, when the differential pressure value is not a pressure value between −1 kPa or more and 0 kPa or less, the CPU 30c determines whether or not the differential pressure value is within a range of larger than 0 kPa to equal to or lower than 5 kPa which is the set pressure value (step S112). The value within a range of larger than 0 kPa to equal to or lower than 5 kPa is previously set.
When the differential pressure value is within a range of larger than 0 kPa to equal to or lower than 5 kPa, the pressure inside the load-lock chamber 14 is determined to be normal and the time of the after-purge in the lot to be performed next is not increased nor decreased and set to be the standard after-purge time, i.e., about seven seconds (step S113).
In addition, in the process of the step S112, when the differential pressure value is larger than 5 kPa, the CPU 30c determines that the pressure inside the load-lock chamber 14 is not normal and decreases the after-purge time in the lot to be performed next by a preset time (step S114). The time to be decreased is, e.g., about one second. Here, the value of 5 kPa is a third set pressure value.
Therefore, the after-purge time in the lot to be performed next is about six seconds obtained by subtracting one second from the standard after-purge time. The time of “−1 second” decreased in the process of the step S114 is stored in the memory 30b.
Then, when any of the processes of the steps S111, S113, or S114 is finished, the CPU 30c obtains a sum of the increased and decreased after-purge times stored in the memory 30b in the processes of the steps S111, S113, or S114 (step S115). Next, the CPU 30c determines whether or not the sum of the after-purge times obtained is three seconds or longer (step S116).
When the sum of the after-purge times is three seconds or longer, the CPU 30c outputs an overtime alarm signal indicating that the sum is three seconds or longer and then stops the ashing process of a semiconductor wafer to be performed next (step S117). In addition, the alarm server 33 receives the overtime alarm signal and then activates an alarm.
When the monitor 34 receives the overtime alarm signal, the monitor 34 displays a message indicating that maintenance of the ashing apparatus 10 is recommended and a message indicating that the ashing process of a semiconductor wafer to be performed next has been stopped, for example.
Note that, in the process of the step S117, the ashing process of a semiconductor wafer to be performed next may not be stopped and only the display of message(s) and activation of an alarm may be performed.
When the sum of after-purge times is three seconds or longer, there is a possibility that any trouble in the vacuum system of the ashing apparatus has occurred. More specifically, a sealing failure of the valve 21 in
In the venting process, although the valve 21 is closed, the vacuum pump 22 in
Accordingly, recommendation of maintenance of the ashing apparatus 10 is displayed. In this manner, the possibility of early detection of trouble with the ashing apparatus 10 can be increased.
In the process of the step S116 in
In this manner, in the process of the step S103 in the lot to be performed next, the after-purge is performed for an after-purge time to which a time set in any of the steps S111, S113, and S114 is added.
Note that the numerical values determined in the respective processes of the steps S108, S110, and S112 in
In the case of such an ashing apparatus, regarding the determination in the process of the step S108, it may be designed such that whether or not the differential pressure value is equal to or lower than −1.5 kPa is determined.
In the same manner, as to the time of “1 second” to be increased or decreased to or from the standard after-purge time, it is not particularly limited but may be optional. For example, the increasing/decreasing time may be 0.5 second or 1.5 seconds.
Alternatively, when increasing time from the standard after-purge time, the time to be increased may be longer than the time to be decreased from the standard after-purge time. Alternatively, in the opposite way, when decreasing time from the standard after-purge time, the time to be decreased may be longer than the time to be increased from the standard after-purge time.
<Example of Manufacturing Process>
The ashing apparatus 10 of
Thereafter, by using the ashing apparatus 10 in
In such an ashing process, by using the ashing apparatus 10 of the present embodiment, failures such as breakage of semiconductor wafers can be suppressed. In this manner, manufacturing failures of a semiconductor device can be reduced.
<Comparative Example of Pressure Transition Inside Load-Lock Chamber>
In
Subsequently, also in the stability corresponding to the process of the step S104 in
In contrast, in the case illustrated in
For example, in a case in which calibration of the pressure meter is insufficient, the pressure meter is out of order, or the like, as illustrated in
In the same manner, also as to the atmospheric pressure sensor, in the case of calibration failure, malfunction, or the like, even when the pressure value is lower than 730 Torr, the atmospheric pressure signal may be outputted due to an erroneous detection.
In this manner, when the main purge is finished in a state where the pressure inside the load-lock chamber is 730 Torr or lower, the pressure inside the load-lock chamber is not increased also in the after-purge, so that the pressure inside the load-lock chamber becomes lower than 760 Torr even after the stability is finished.
That means that the atmosphere gate valve 16b is opened in a state where the pressure inside the load-lock chamber is negative and it makes the pressure inside the load-lock chamber jump up to about 760 Torr.
As illustrated in
The semiconductor wafers 24 jumped by the wind pressure come into contact with a rack 23a included in the place rack 23 above the semiconductor wafers, thereby causing breakage or the like of the semiconductor wafers 24.
Conversely, in the case of the ashing apparatus 10 in
In this manner, breakage of a semiconductor wafer to be performed next can be prevented. In addition, transferring a semiconductor wafer that may be broken to the next process can be prevented.
Further, when there is no possibility of jumping of a semiconductor wafer but the pressure inside the load-lock chamber cannot be sufficiently increased in the standard after-purge time, that is, in the case of the process of the step S111 in
In addition, when increasing of the standard after-purge time is performed repeatedly, there is a possibility that sealing failure of the valve 21 in
In this manner, manufacturing failures of a semiconductor device caused by trouble with the ashing apparatus 10 can be reduced.
As described above, damages and the like of semiconductor wafers in the ashing process of the ashing apparatus 10 can be prevented. Accordingly, reliability of a semiconductor device can be improved.
In the foregoing, the invention made by the inventors of the present invention has been concretely described based on the embodiments. However, it is needless to say that the present invention is not limited to the foregoing embodiments and various modifications and alterations can be made within the scope of the present invention.
While the asking apparatus has been described in the embodiment, the embodiment is not limited to this. For example, the embodiment can be used in general apparatuses for vacuum processes like a vacuum vapor-deposition apparatus, a sputtering apparatus, or the like.
The present invention includes various modifications and is not limited to the embodiments. For example, the embodiments are described in detail to simplify the explanation of the present invention. Thus, it is not always necessary to provide all the described configurations.
Moreover, the configurations of one of the embodiments may be partially replaced with those of the other embodiment or the configurations of one of the embodiments may further include the configurations of the other embodiment. Alternatively, the configurations of the embodiments may partially allow the addition of other configurations, deletion, and replacement.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-164928 | Aug 2015 | JP | national |
