Patent Application
20090162170
1. Field of the Invention
The present invention relates to a semiconductor manufacturing apparatus of vacuum load lock type. It also relates to a structure and operating method of a compact sheet-feed semiconductor apparatus capable of processing wafers efficiently and continuously or simultaneously.
2. Description of the Related Art
In general, conventional semiconductor manufacturing apparatuses of vacuum load lock type, which are used in the manufacture of integrated semiconductor circuits, comprise a load lock chamber, transfer chamber and multiple reaction chambers (processing chambers) connected to the transfer chamber. Each chamber uses a wafer transfer robot to automatically feed wafers, and is operated as follows. First, an atmospheric robot installed in a mini-environment carries a wafer into the load lock chamber from a wafer cassette or FOUP (a box equipped with removable wafer cassettes and front-opening interface). Next, the load lock chamber is evacuated to a vacuum state, after which a vacuum robot inside the common polygonal transfer chamber is used to transfer the wafer to each reaction chamber. Once the wafer has been processed in the reaction chamber, the wafer is transferred to the load lock chamber via the vacuum robot. Finally, the interior of the load lock chamber is restored to atmosphere and the processed wafer is carried out to a cassette or FOUP via the atmospheric robot. This type of apparatus is generally called a “cluster tool.” However, an attempt to configure a “cluster tool” apparatus offering higher productivity (throughput) will increase the installation space and width (faceprint) of the apparatus.
In the meantime, apparatuses have been developed where the load lock chamber is equipped with a transfer mechanism, and reaction chambers are provided adjoining the load lock chamber via a gate valve (GV) in order to reduce the footprint of the apparatus. However, this configuration also presents the same problem; i.e., increasing the number of reaction chambers to configure an apparatus offering higher throughput will still increase the installation space and faceprint of the apparatus. Also, the number of reactors that can be handled by one atmospheric robot is limited, and therefore an increase in the number of reaction chambers necessitates the numbers of atmospheric robots, FOUP openers, etc., to be increased accordingly.
In an embodiment of the present invention aimed at solving at least one of the problems mentioned above, a semiconductor manufacturing apparatus of vacuum load lock type is provided wherein said semiconductor manufacturing apparatus is characterized in that it comprises a load lock chamber, a reaction chamber adjoining the load lock chamber, and an atmospheric transfer robot installed outside the load lock chamber, where the load lock chamber has a wafer transfer mechanism that can be operated in vacuum and the chamber structure that allows wafers to be exchanged between the atmospheric transfer robot and each chamber is stacked vertically over at least two levels.
In another embodiment, a semiconductor manufacturing apparatus according to the embodiment described above is provided, wherein said semiconductor manufacturing apparatus is characterized in that a FOUP stocker with at least one FOUP (a box equipped with removable wafer cassettes and front-opening interface) opener is provided in front of the atmospheric transfer robot so that multiple FOUPs can be carried in/stored and set/carried out temporarily, and therefore wafers can be exchanged between the FOUP stocker and atmospheric transfer robot.
In another embodiment, a semiconductor manufacturing apparatus according to either of the embodiments described above is provided, wherein said semiconductor manufacturing apparatus is characterized in that at least two pairs of load lock chamber and reaction chamber are installed in the horizontal direction, and a FOUP stocker with at least two FOUP openers capable of storing multiple FOUPs temporarily is provided in front of the atmospheric transfer robot so that wafers can be exchanged between the FOUP stocker and atmospheric transfer robot.
In yet another embodiment, a semiconductor manufacturing apparatus according to any one of the embodiments described above is provided, wherein said semiconductor manufacturing apparatus is characterized in that the atmospheric transfer robot comprises at least two robots having a single wafer transfer arm or one robot having at least two wafer transfer arms, and at least two wafers are carried out of the FOUP almost simultaneously and installed in the wafer transfer mechanism inside the load lock chamber almost simultaneously.
For purposes of summuarizing the invention and the advantages achieved over the related art, certain objects and advantages of the invention are described in this disclosure. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.
Further aspects, features and advantages of this invention will become apparent from the detailed description of the preferred embodiments which follow.
These and other features of this invention will now be described with reference to the drawings of preferred embodiments which are intended to illustrate and not to limit the invention. The drawings are oversimplified for illustrative purposes and are not to scale.
The present invention will be explained in detail with reference to preferred embodiments. However, the preferred embodiments are not intended to limit the present invention.
The semiconductor manufacturing apparatus and method proposed by the present invention are explained by referring to the drawings.
Examples of the semiconductor manufacturing apparatus pertaining to the present invention is explained.
The mini-environment section 103 has a single interior space 9 in which an atmospheric robot 6 is placed to carry in/out wafers between the FOUP section 102 and process section 101. The FOUP section 102 has a wafer cassette 4 with a FOUP opener 5, and the FOUP opener 5 functions as an open front interface 10. The atmospheric robot 6 can be moved horizontally between the two wafer cassettes 4 and two load lock chambers 1. Although the robot can also move vertically between the load lock chamber 1 and cooling stage 1 to move vertically over the wafer cassette, the robot cannot move any further in the vertical direction (the drive part itself does not move in the vertical direction).
For your reference, six buffer storage 42 units are installed in the FOUP stocker 41 to feed wafer cassettes 4.
If there is only one FOUP opener, the atmospheric robot stands by while the FOUPs are changed after the completion of wafer processing, until the changeover operation is completed, and this reduces the throughput. It would be efficient to provide at least two FOUP openers, because processing of wafers in the second FOUP can be started without delay once the processing of wafers in the first FOUP has completed.
The speed of 240 wafers per hour corresponds to 9.6 FOUPs per hour, which requires a FOUP to be fed and carried out every 6.25 minutes. However, the FOUP feed rate is unstable on actual production lines, and therefore an ingenuous solution is required. If the processing speed of the manufacturing apparatus is very high, for example, FOUPs cannot be fed fast enough and the FOUP feed rate may have to be limited. To resolve this problem, a FOUP stocker 41 capable of temporarily storing multiple FOUPs is equipped in the apparatus shown in
For your information, the atmospheric robot is installed on XY slide-rails 27 and controlled automatically in order to widen the moving range of the robot itself to allow wafers to be placed in/taken out of the load lock chambers provided horizontally and vertically.
Table 1 compares two apparatus configurations having the same throughput, one comprising three units of the conventional apparatus illustrated in
As shown by Table 1, the apparatus according to the present invention achieves the same throughput at approx. 33% less cost and approx. 60% less footprint and faceprint.
Next, the process sequences of the apparatuses shown in
Next, the process sequence of the apparatus shown in
Since a FOUP needs to be input every 285 seconds (4 minutes 45 seconds), a FOUP stocker is required for this apparatus in practical operation. The FOUP stocker may preferably be RICSS300 made by Rorze or equivalent. There are six FOUP buffer storage units to support OHT.
Two atmospheric transfer robots are installed, and each robot has an independent right-left slide axis so that wafers can be transferred out of the FOUP and placed in the LLC, or vice versa, simultaneously on the right and left sides. Also, there is a vertical slide axis to cover three vertical levels.
The sequence is explained according to the flow of wafers.
[1]The automatic FOUP transfer system places the first FOUP (hereinafter referred to as “F1”) in the FOUP stocker on the apparatus side.
[2] The FOUP stocker sets the FOUP in load port 1. Specifically, every time a wafer is transferred by each atmospheric robot from the FOUP to the load lock chamber, the total number of wafers decreases by 2 from 25. Also, with each transfer by each atmospheric robot of a wafer that has been cooled to normal temperature (temperature at which the wafer can be stored in the FOUP) on the cooling stage, the total number of wafers increases by 2.
The second FOUP (hereinafter referred to as “F2”) is placed within 285 seconds (4 minutes 45 seconds). In reality, however, it is not practical to feed FOUPs at a cycle of less than 5 minutes, and thus a FOUP stocker needs to be installed to mitigate the FOUP placement cycle.
[3] The front end indicates the time required by atmospheric robots 1 and 2 to place wafers on the end effectors. To be specific, atmospheric robot 1 transfers wafer B1 (a wafer before deposition is indicated by B, followed by a sequential value) from F1 and places it in load lock chamber 1, while atmospheric robot 2 simultaneously places wafer B2 in load lock chamber 2. The time required for the placements is 10 seconds.
[4] There are first, second and third levels of main modules, where each module has one set of load lock chambers capable of storing two wafers, one set of load lock pumps, and two sets of reaction chambers.
To be specific, wafer B1 is placed in load lock chamber 1, and wafer B2 is placed in load lock chamber 2, after which the load lock chambers are evacuated. The evacuation time is 10 seconds.
After the evacuation, the wafers are placed in the reaction chambers. The wafer changeover time is 10 seconds.
After the wafers have been changed, deposition is started simultaneously in reaction chambers 1 and 2 (the deposition time is assumed as 75 seconds). The load lock chambers are opened to atmosphere while deposition is in progress in the reaction chambers, and the next pre-deposition wafers B7/B8 are placed and the load lock chambers are evacuated.
After films have been deposited on the wafers, the wafers are changed. Wafers B7/B8 are transferred from the load lock chambers and placed in the reaction chambers, while wafers A1/A2 (a wafer completing deposition is indicated by A, followed by a sequential value) are transferred from the reaction chambers and placed in the load lock chambers.
Once a wafer has been transferred and placed, deposition is started in each reaction chamber.
When the load lock chambers are opened to atmosphere, wafers B13/B14 are transferred from F1 and placed, while wafers A1/A2 are placed on the cooling stages. At this time, the atmospheric robots pick up wafers B13/B14 from F1 upon start of opening of the load lock chambers as a trigger, after which the robots stand by in front of the load lock chambers. This reduces the wafer placement time to 5 seconds after the opening of the load lock chamber to atmosphere (normally it takes 10 seconds). The atmospheric robots move wafers A1/A2 to the cooling stages immediately after placing wafers B13/B14 in the load lock chambers, which also reduces the wafer placement time to 5 seconds (normally it takes 10 seconds).
As for wafer placement from the cooling stage to FOUP, this placement is performed after the next wafer completing deposition has been placed on the cooling stage, because the cooling time normally is set to 60 seconds. In this example, wafers Z1/Z2 are returned from cooling stages 1 and 2 to F1 after A7/A8 have been placed on the cooling stages.
The above processing is repeated, which requires that the reaction chambers be cleaned after several deposition cycles. In this example, one cleaning is assumed after five deposition cycles (5D1C). In other words, the reaction chambers are cleaned after A25/A26 have been collected into the load lock chambers.
The above methods allow the atmospheric transfer robots to place wafers without having their transfer speeds limited, and this configuration comprising two atmospheric robots, two FOUP openers and one mini-environment can achieve three times the running throughput of the apparatus shown in
In the present disclosure where conditions and/or structures are not specified, the skilled artisan in the art can readily provide such conditions and/or structures, in view of the present disclosure, as a matter of routine experimentation. For example, the system disclosed in U.S. Pat. No. 6,630,053 can be used when practicing an embodiment of the present invention, the disclosure of which is herein incorporated by reference it its entirety.
It will be understood by those of skill in the art that numerous and various modifications can be made without departing from the spirit of the present invention. Therefore, it should be clearly understood that the forms of the present invention are illustrative only and are not intended to limit the scope of the present invention.
