JP5545488B2 - Plasma processing equipment - Google Patents

Description

  The present invention relates to a plasma processing apparatus in which a substrate to be processed is loaded into a reaction chamber in a state of being placed on a tray, and plasma processing is performed.

In a plasma processing apparatus that performs processing such as etching processing and film forming processing on a semiconductor wafer (hereinafter simply referred to as “wafer”) in a vacuum reaction chamber, the wafer can be transported while being placed on a tray. Has been done.
For example, Patent Document 1 includes a reaction chamber for processing a wafer and a preheating chamber for preheating an unprocessed wafer, and the wafer is placed on a tray between the reaction chamber and the preheating chamber. A transported substrate processing apparatus is disclosed.
Patent Document 2 discloses a substrate processing apparatus including a reaction chamber for processing a wafer, a transfer chamber for transferring a wafer, and a tray stage having a heater provided in the transfer chamber. In the substrate processing apparatus of Patent Document 2, a wafer carried into a transfer chamber is placed on a tray stage via a tray.

In the substrate processing apparatus of Patent Document 1, the wafer is transferred from the preheating chamber to the reaction chamber while being placed on the tray, and then taken out from the tray and processed. The tray after the wafer is taken out is carried out of the reaction chamber. On the other hand, in the substrate processing apparatus of Patent Document 2, a wafer is taken out from a tray on a tray stage in a transfer chamber by a transfer arm or the like and transferred into a reaction chamber. As described above, in Patent Documents 1 and 2, it is necessary to take a wafer into and out of the tray when the wafer is carried into or out of the reaction chamber. In particular, when a plurality of wafers are accommodated in a reaction chamber such as a small-diameter wafer and plasma processing is performed, the time for taking the wafers in and out of the tray becomes long and the production efficiency is poor.
Therefore, a plasma processing apparatus is provided in which a wafer is loaded into a reaction chamber in a state where it is placed on a tray and plasma processing is performed as it is.

  The number of wafers placed on one tray varies depending on the size of the wafer and the tray. For example, when the tray diameter is 380 mm and the wafer diameter is 2 inches, several tens of wafers are placed on one tray. Is placed. When plasma processing is performed with a plurality of wafers placed on the tray in this way, the uniformity of the plasma processing is ensured by ensuring that the surfaces of the wafer and the tray are flush with each other in order to ensure stability during transportation. In order to improve the quality, a tray provided with a countersink part (concave part) having substantially the same size and shape as the wafer is used.

Plasma treatment includes a film formation process performed at a high temperature of 200 ° C. or higher and an etching process performed at a low temperature of about −100 ° C. The processed wafer or tray after the plasma processing is performed at such a high temperature or low temperature is brought into a high temperature state or a low temperature state and is carried out of the reaction chamber by the transfer robot. Thereafter, the wafer is placed on a tray stage outside the reaction chamber, and the processed wafer is taken out of the tray by the transfer robot.
The transfer robot stores in advance the position information of the wafer on the tray, and the transfer robot captures the processed wafer by a capturing means such as a Bernoulli chuck based on the position information and removes it from the countersink. . Further, the transfer robot takes out an unprocessed wafer from a wafer case or the like and places it on the countersink portion of the tray.

When a large number of wafers are placed on the tray, it takes about several minutes for the transfer robot to replace all processed wafers on the tray with unprocessed wafers. When the time for replacing the wafer on the tray becomes longer, the heated and expanded tray is gradually cooled and contracted during the wafer replacement operation, and the dimensions of the tray change. Particularly large changes dimensions in the case of aluminum metal tray, for example, when the thermal expansion coefficient of 24 × 10 ^-6 / K, a diameter of a typical aluminum tray 380mm is, 200 ° C. to 250 DEG The diameter shrinks by 1.5-2mm or more while it falls from room temperature to room temperature.

If the size of the tray changes greatly in this way, the position of the counter-sink portion of the tray, that is, the position of the wafer changes greatly, so that the transfer robot cannot accurately capture the wafer by the capturing means, or the normal capturing position. There is a risk of catching a different position. If a position different from the normal capturing position is captured, the processed wafer and the wafer case may come into contact with each other and damage the wafer when the processed wafer is stored in the wafer case. Further, if the position of the countersink portion on the tray changes, an unprocessed wafer cannot be accurately placed on the countersink portion of the tray.
Such a phenomenon can occur not only when a high-temperature tray is cooled, but also when a low-temperature tray is heated to room temperature.

  On the other hand, Patent Document 3 discloses a teaching-type transfer robot in which operations are successively fine-tuned based on the result of image recognition of the amount of displacement of the countersink portion of the wafer or tray by a CCD camera. Yes.

JP 2001-239144 A Japanese Patent Laid-Open No. 10-233423 JP 2008-066372

  However, in the case of the transfer robot of Patent Document 3, in order to accurately recognize the displacement amounts of all the many wafers and many countersinks placed on the tray, the number of wafers or countersink The number of cameras corresponding to the number of copies must be provided. In addition, if the camera is scanned to acquire an image of the entire tray, the number of cameras can be reduced. In this case, a camera scanning mechanism is required.

  The problem to be solved by the present invention is that even if the tray becomes hot or cold due to plasma processing with the substrate to be processed placed on the tray, the processing is accurately performed at a predetermined position of the tray with a simple configuration. It is an object of the present invention to provide a plasma processing apparatus capable of placing a substrate and taking out a substrate to be processed from the tray.

The present invention made to solve the above-mentioned problems is a plasma processing apparatus for carrying out plasma processing of a substrate to be processed by carrying it into a reaction chamber in a state where the substrate to be processed is placed on a tray.
a) a tray stage provided outside the reaction chamber;
b) a tray transfer mechanism for transferring the tray on which the substrate to be processed is placed between the tray stage and the reaction chamber;
c) A substrate transfer mechanism for taking out the substrate to be processed from the tray on the tray stage and placing the substrate to be processed before the plasma processing on the tray on the tray stage;
d) Temperature maintaining means for maintaining the temperature of the tray placed on the tray stage in a predetermined temperature range.

Further, the present invention provides a first temperature detection means for detecting the temperature of the tray in the reaction chamber during the plasma processing,
Second temperature detecting means for detecting the temperature of the tray placed on the tray stage;
Based on the detection result of the first temperature detection means and the detection result of the second temperature detection means, the temperature of the tray on the tray stage is maintained at the temperature of the tray in the reaction chamber during the plasma processing. The apparatus further comprises control means for controlling the temperature maintaining means.

  Furthermore, the present invention preferably includes a tray transfer chamber provided between the reaction chamber and the tray stage.

  According to the plasma processing apparatus of the present invention, the temperature of the tray placed on the tray stage installed outside the reaction chamber is maintained within a predetermined temperature range by the temperature maintaining means. For this reason, after the tray that has become hot or cold due to the plasma treatment is taken out of the reaction chamber and placed on the tray stage, the temperature of the tray changes greatly and contracts or expands. Can be prevented. Therefore, since it is possible to prevent the mounting position of the substrate to be processed on the tray from being changed, the substrate to be processed can be reliably captured from the tray on the tray stage, and the substrate to be processed is accurately placed at a predetermined position on the tray. It can be mounted on.

The top view which shows schematic structure of the plasma processing apparatus which concerns on one Example of this invention. The side view which shows schematic structure of a plasma processing apparatus.

  In the plasma processing apparatus according to the present invention, the substrate to be processed is loaded into the reaction chamber while being placed on the tray, and plasma processing is performed. The tray on which the substrate to be processed is placed is placed on a placement table in the reaction chamber. The mounting table is preferably provided with an electrostatic chuck for electrostatically attracting the tray, a mechanism for cooling the tray and the substrate to be processed with a cooling gas, or a mechanism for heating the tray and the substrate to be processed. Examples of the plasma treatment include etching treatment and film formation treatment.

The plasma processing apparatus of the present invention is provided with a tray stage on which a tray is placed outside the reaction chamber. The tray is a member for transporting the substrate to be processed between the tray stage and the reaction chamber, on which one or a plurality of substrates to be processed are placed. Examples of the material of the tray include alumina and aluminum, but an aluminum tray is preferable in terms of excellent thermal conductivity.
Moreover, it is preferable that a countersink part (concave part) having substantially the same size and shape as the substrate to be processed is provided on the tray surface. By using such a tray, the substrate to be processed can be stably conveyed. Further, the surface of the substrate to be processed and the tray can be flush with each other, and the uniformity of the plasma processing is improved.

  The substrate to be processed after the plasma treatment in the reaction chamber is unloaded from the reaction chamber while being placed on the tray, and is transferred to the tray stage by the tray transport mechanism. The tray stage is provided with temperature maintaining means for maintaining the temperature of the tray within a predetermined temperature range. As a result, the temperature of the tray after the plasma treatment can be maintained, so that the high temperature tray after the plasma treatment is gradually cooled and contracted, or the low temperature tray is gradually heated and expanded. Can be prevented. Therefore, it is possible to prevent the position of the countersunk portion provided on the tray and the position of the substrate to be processed placed on the tray from changing as much as possible. Therefore, even when an aluminum tray having a large thermal expansion coefficient is used, the substrate transfer mechanism can reliably capture the substrate to be processed on the tray. In addition, the substrate to be processed can be accurately transferred to a predetermined position on the tray. The temperature maintaining means for maintaining the temperature of the tray within a predetermined temperature range can be achieved by embedding an electric heater in the tray stage, providing an infrared heater at the top of the tray stage, or circulating a refrigerant in the tray stage. Can be configured.

  The present invention also provides a first temperature detecting means for detecting the temperature of the tray in the reaction chamber during the plasma processing, a second temperature detecting means for detecting the temperature of the tray placed on the tray stage, and the first It is preferable to provide a control means for controlling the temperature maintaining means based on the detection result of the temperature detection means and the detection result of the second temperature detection means. With such a configuration, the temperature of the tray placed on the tray stage can be adjusted to be substantially the same as the temperature of the tray during plasma processing.

  Furthermore, according to the present invention, if a tray transfer chamber is provided between the reaction chamber and the tray stage so that the transfer chamber can be switched to atmospheric pressure or vacuum, the reaction chamber can always be kept in a vacuum state. Further, if a heating mechanism or a cooling mechanism for maintaining the temperature of the tray being transferred is provided in the transfer chamber, a change in the temperature of the tray during transfer from the reaction chamber to the tray stage can be suppressed.

  A specific embodiment of the plasma processing apparatus of the present invention will be described below with reference to FIGS. 1 and 2 show the configuration of the plasma processing apparatus 1 according to the present embodiment. The plasma processing apparatus 1 of the present embodiment includes a vacuum reaction chamber 2, a transfer chamber (load lock chamber) 4, an atmospheric chamber 6, between the vacuum reaction chamber 2 and the transfer chamber 4, and between the transfer chamber 4 and the atmospheric chamber 6. Gate valves 8 and 10 are provided.

Inside the vacuum reaction chamber 2, a shower head 12 that is a supply port for source gas, a mounting table 16 on which the tray 14 is mounted, and an infrared temperature sensor 18 that detects the temperature of the tray 14 on the mounting table 16 (the present invention Corresponding to the first temperature detecting means). The mounting table 16 is provided with a heater 20 and an electrostatic chuck (not shown). In the present embodiment, the shower head 12 also serves as the upper electrode, and the mounting table 16 also serves as the lower electrode.
The tray 14 is made of aluminum, and a plurality of countersunk portions (concave portions) 14a are provided on the surface thereof. A semiconductor wafer W (hereinafter simply referred to as “wafer”) as a substrate to be processed is placed on these countersink portions 14a. The size (inner diameter and depth) of the countersink 14a is set to be substantially the same as the outer diameter and thickness of the wafer W, and the wafer W accommodated in the countersink 14a is flush with the surface of the tray 14. Become.

  The transfer chamber 4 is provided with a robot 22 that transfers the tray 14 between the vacuum reaction chamber 2 and the atmospheric chamber 6. Although not shown, the transfer chamber 4 is connected to a decompression means for decompressing the interior thereof.

  The atmosphere chamber 6 has a tray stage 30, a wafer case 32 for storing the wafer W, a transfer robot 34 for moving the wafer W between the tray stage 30 and the wafer case 32, and the temperature of the tray 14 on the tray stage 30. An infrared temperature sensor 36 (corresponding to the second temperature detection means of the present invention) is provided. The robot 34 has an arm 34a and a Bernoulli chuck 34b as a substrate capturing means attached to the tip of the arm 34a. The robot 34 stores in advance the countersink 14a of the tray 14 on the tray stage 30. The Bernoulli chuck 34b sucks and takes out the plasma-treated wafer W from the countersink 14a of the tray 14 to obtain a wafer case 32. Store in. Further, the wafer W is chucked and taken out from the wafer case 32 and stored in the countersink 14 a of the tray 14 on the tray stage 30. The tray stage 30 is provided with an infrared heater 38. In FIGS. 1 and 2, the tray 14 and the wafer W are in a state of being placed on the tray stage 30 of the atmospheric chamber 6.

  The heater 20 and the infrared heater 38 are controlled by the control device 40. A detection signal of the infrared temperature sensor 18 is input to the control device 40, and the heater 20 is controlled based on this signal. The control device 40 is also input with a detection signal of the infrared temperature sensor 36, and the temperature of the tray 14 on the tray stage 30 is determined during the plasma processing based on the detection signals of the infrared temperature sensors 18 and 36. The output of the infrared heater 38 is adjusted so as to be substantially the same as the temperature of the tray 14 in the vacuum reaction chamber 2. In this embodiment, the infrared heater 38 constitutes a temperature maintaining means.

Next, the operation of the plasma processing apparatus 1 according to the present embodiment will be described.
First, an unprocessed wafer W is taken out from the wafer case 32 by the robot 34 and placed on the countersink 14 a of the tray 14 on the tray stage 30. At this time, the tray 14 is heated to a predetermined temperature by the infrared heater 38 in the tray stage 30.
After the wafer W is placed on the countersink 14 a of the tray 14, the gate valve 10 is opened, and the tray 14 on the tray stage 30 is transferred into the transfer chamber 4 by the robot 22 in the transfer chamber 4. Thereafter, the gate valve 10 is closed, and the inside of the transfer chamber 4 is reduced to a predetermined pressure. Subsequently, the gate valve 8 is opened, and the tray 14 is transported into the vacuum reaction chamber 2 by the robot 22 and placed on the mounting table 16. The tray 14 mounted on the mounting table 16 is attracted by the electrostatic chuck and heated by the heater 20.

When the temperature of the tray 14 of the mounting table 16 reaches a predetermined temperature, tetraethoxysilane (TEOS) and oxygen, which are film forming raw material gases, are introduced from the shower head 12 into the vacuum reaction chamber 2. Then, when a high frequency power source is applied between the lower electrode and the upper electrode and the source gas is turned into plasma, an oxide film is formed on the surface of the wafer W. The detection signal of the infrared temperature sensor 18 during the plasma processing is input to the control device 40 and stored.
When the plasma processing is completed, the gate valve 8 is opened, and the tray 14 on the mounting table 16 is transferred into the transfer chamber 4 where the pressure is reduced to a predetermined pressure by the robot 22. Subsequently, the gate valve 8 is closed, the inside of the transfer chamber 4 is returned to atmospheric pressure, the gate valve 10 is opened, and the tray 14 is transferred onto the tray stage 30 by the robot 22.

  When the tray 14 is transferred onto the tray stage 30, the control device 40 determines that the temperature of the tray 14 is in the plasma processing based on the detection signal of the infrared temperature sensor 36 and the detection signal of the infrared temperature sensor 18 during the plasma processing. The output of the infrared heater 38 is adjusted so as to be substantially the same as the temperature of the tray 14. Thereby, the tray 14 of the tray stage 30 is maintained at the temperature of the tray 14 during the plasma processing.

  In this state, the plasma-processed wafer W is adsorbed by the Bernoulli chuck 34 b of the robot 34 in the atmosphere chamber 6 and stored in the wafer case 32 from the tray 14 on the tray stage 30. When the wafers W are attracted from all the countersink portions 14a of the tray 14 and stored in the wafer case 32, the unprocessed wafers W in the wafer case 32 are subsequently attracted by the Bernoulli chuck 34b of the robot 34, and the tray It is placed on the tray 14 on the stage 30.

  While such a wafer W replacement operation is performed, the temperature of the tray 14 on the tray stage 30 is maintained at the temperature during the plasma processing, and the position of the wafer W on the tray 14 and the countersink 14a. The position does not change. Therefore, the robot 34 can accurately suck the predetermined position of the wafer W on the tray 14. Further, the wafer W can be accurately placed on the countersink portion 14a of the tray 14.

  Further, in this embodiment, the temperature of the tray 14 is maintained substantially the same as the temperature during the plasma processing, so that after the unprocessed wafer W is mounted, the tray 14 is mounted on the mounting table 16 in the vacuum reaction chamber 2. There is no need to adjust the temperature by heating the tray 14 with the heater 20 for plasma processing, thereby improving the throughput. Further, the deterioration of the tray 14 due to frequent changes in the temperature of the tray 14 does not occur.

  In the above embodiment, the example in which the temperature of the tray 14 is increased by the plasma processing has been described. However, when the temperature of the tray 14 is decreased by the plasma processing, a refrigerant circulation path is provided inside the tray stage 30. The tray 14 on the tray stage 30 may be cooled. Thereby, the tray 14 on the tray stage 30 can be maintained at a temperature during the plasma processing.

  In the present invention, the wafer W may be prevented from gradually contracting or expanding during the operation of taking out the wafer W from the tray 14 on the tray stage 30 or placing the wafer W on the tray 14. Accordingly, it is not essential that the temperature of the tray 14 placed on the tray stage 30 is the same as the temperature of the tray 14 during plasma processing, and the temperature of the tray 14 on the tray stage 30 is maintained within a predetermined temperature range. It only has to be done. However, if the temperature of the tray 14 on the tray stage 30 is maintained near room temperature, the temperature difference from the tray 14 during the plasma processing increases, so that expansion and contraction due to large temperature changes frequently occur, and the tray 14 Tends to deteriorate. Also, the throughput is reduced. Therefore, considering these circumstances, it is effective to maintain the temperature of the tray 14 during plasma processing.

2 ... Vacuum reaction chamber 4 ... Transfer chamber 6 ... Air chamber 8 ... Gate valve 10 ... Gate valve 12 ... Shower head 14 ... Tray 14a ... Countersink 16 ... Mounting table 18 ... Infrared temperature sensor (first temperature detecting means)
20 ... Heater 22 ... Robot (tray transport mechanism)
30 ... Tray stage 32 ... Wafer case 34 ... Robot (substrate transfer mechanism)
34a ... arm 34b ... Bernoulli chuck 36 ... infrared temperature sensor (second temperature detecting means)
38 ... Infrared heater 40 ... Control device W ... Semiconductor wafer (substrate to be processed)

Claims (3)

In a plasma processing apparatus for carrying a plasma process on a substrate to be processed by carrying the substrate to be processed into a reaction chamber in a state of being placed on a tray,
a) a tray stage provided outside the reaction chamber;
b) a tray transfer mechanism for transferring the tray on which the substrate to be processed is placed between the tray stage and the reaction chamber;
c) A substrate transfer mechanism for taking out the substrate to be processed from the tray on the tray stage and placing the substrate to be processed before the plasma processing on the tray on the tray stage;
d) A plasma processing apparatus comprising temperature maintaining means for maintaining the temperature of the tray placed on the tray stage in a predetermined temperature range. First temperature detection means for detecting the temperature of the tray in the reaction chamber during plasma processing;
Second temperature detecting means for detecting the temperature of the tray placed on the tray stage;
Based on the detection result of the first temperature detection means and the detection result of the second temperature detection means, the temperature of the tray on the tray stage is maintained at the temperature of the tray in the reaction chamber during the plasma processing. The plasma processing apparatus according to claim 1, further comprising control means for controlling the temperature maintaining means.   The plasma processing apparatus according to claim 1, further comprising a tray transfer chamber provided between the reaction chamber and the tray stage.

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