JP2009182094A - Manufacturing method and apparatus for semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect and correct a wafer shift if the wafer shift is made in a chamber processing room of a plasma device used in a stage of manufacturing the semiconductor device. <P>SOLUTION: In the chamber processing room 1, a wafer 2 is conveyed by a conveyance arm 2 and mounted on a lower electrode 3. The wafer 2 is sucked to the lower electrode 3 and subjected to plasma processing, and dechucked after the processing is completed. Then the position of the wafer 2 is confirmed by an infrared sensor 16. When the infrared sensor 16 reacts at this time, a shift of the wafer in the reaction direction is detected. When the wafer shift is detected by the infrared sensor 16, a wafer position feedback system 44 feeds the direction and amount of the wafer shift back to the conveyance arm 42, and the conveyance arm 42 is inserted into the chamber processing room 1 to carry the wafer 2 out. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a semiconductor device manufacturing method and a manufacturing apparatus, and more particularly to a manufacturing method and a manufacturing apparatus for holding a target object (semiconductor substrate) by electrostatic adsorption and performing plasma processing.

  In a conventional semiconductor device manufacturing process, plasma processing is frequently used for a film forming process for forming various material films and a dry etching process for forming wirings, contact holes, and the like. FIG. 5 shows a schematic configuration of a plasma processing apparatus used for such plasma processing.

  First, the configuration of a conventional plasma processing apparatus will be described. As shown in FIG. 5, the plasma processing apparatus 100 includes a chamber processing chamber 1 and a chamber preliminary chamber 41.

  Inside the hermetically sealed chamber processing chamber 1, for example, a lower electrode 3 serving also as a mounting table (stage) for an object to be processed (hereinafter referred to as a wafer 2) such as a semiconductor wafer is provided. An upper electrode 6 is provided at a position facing the lower electrode 3 through a top plate 21 that can transmit electromagnetic waves. The upper electrode 6 is composed of, for example, a planar coil. A high frequency power source 4 that applies high frequency power to the lower electrode 3 is connected to the lower electrode 3. The upper electrode 6 is connected to a high frequency power source 7 that applies high frequency power to the upper electrode 6.

  A gas introducing portion 9 for introducing a process gas such as a material gas or an etching gas into the chamber processing chamber 1 is connected to the side wall of the chamber processing chamber 1, and an exhaust portion 8 is provided below the side wall.

  In addition, a transfer arm 42 as a wafer transfer mechanism is installed inside the chamber preliminary chamber 41. The chamber processing chamber 1 and the chamber preliminary chamber 41 are partitioned by a gate valve 43.

  A conventional wafer processing method will be described with reference to FIG. First, the gate valve 43 is opened, and the transfer arm 42 on which the wafer 2 is mounted is inserted from the chamber preliminary chamber 41 into the chamber processing chamber 1. Then, the lift pins 15 are raised and stopped at a position higher than the transfer arm 42, and the wafer 2 is separated from the transfer arm 42. Thereafter, the transfer arm 42 is stored in the chamber preliminary chamber 41, the gate valve 43 is closed, the lift pins 15 are lowered, and the wafer 2 is placed on the lower electrode 3.

  Next, when the high frequency power supply 7 applies high frequency power to the upper electrode 6 in a state where the process gas is introduced into the chamber processing chamber 1 through the gas introduction unit 9, process gas plasma is generated in the chamber processing chamber 1. . The surface of the wafer 2 is subjected to plasma processing by this plasma. At this time, the high frequency power source 4 applies high frequency power to the lower electrode 3 in order to generate a bias. The pressure in the chamber processing chamber 1 is maintained at a predetermined value by adjusting the exhaust amount of the exhaust unit 8.

  Further, in order to fix the wafer 2 on the lower electrode 3, an electrostatic adsorption electrode is adopted as the lower electrode 3. As is well known, the electrostatic adsorption electrode has a structure in which the electrode is sandwiched between thin films made of polyimide, for example. When high-voltage direct-current power is applied to this electrode from the direct-current high-voltage power supply 10, the wafer 2 placed on the surface of the lower electrode 3 (electrostatic attracting electrode) is applied to the lower electrode 3 by electroadhesive force (electrostatic attracting force). Adsorbed and held.

  At the same time, in the electrostatic adsorption electrode, an inert medium gas such as He (hereinafter referred to as backside gas) is introduced into the back surface of the wafer 2 from the backside gas introduction path 11 having an open end in the lower electrode 3. The Since the back surface of the wafer 2 and the surface of the lower electrode 3 are not microscopically microscopically, the backside gas flows through the gap. At this time, the pressure (flow rate) of the backside gas supplied from the backside gas supply device 12 feeds back the measurement value of the backside gas pressure measurement device 13 so that no wafer jump occurs, that is, a DC high-voltage power supply. The wafer 2 is adjusted to a range in which the wafer 2 is not detached from the surface of the lower electrode 3 against the electroadhesive force caused by the DC high-voltage power applied by 10.

  When the plasma processing of the wafer 2 is completed, the DC high voltage power supply 10 stops the application of the DC high voltage power or reduces the DC high voltage power to be applied, thereby causing the electroadsorption between the lower electrode 3 and the wafer 2. The power is weakened (hereinafter referred to as dechuck). Thereafter, the lift pins 15 are raised to form a space between the lower electrode 3 and the wafer 2. The transfer arm 42 is inserted into this space, and the wafer 2 is unloaded from the lower electrode 3 to the chamber preliminary chamber 41.

  Dechucking defects frequently occur at the time of dechucking in the wafer processing method described above. Even immediately after the DC high-voltage power supply 10 stops applying the DC high-voltage power, the charge generated due to the DC high-voltage power does not immediately disappear from the wafer 2. For this reason, a relatively large electroadhesive force remains on the wafer 2.

  Then, when the lift pins 15 lift up, stresses other than the weight of the wafer 2 are generated as lift-up drag due to the remaining electroadhesive force, so that the balance of stress is lost and the wafer jumps. In this case, the wafer 2 comes into contact with a member in the chamber 1 such as the focus ring 5, and foreign matter is generated on the wafer 2 or the wafer 2 is displaced.

  The reason why the charge generated due to the DC high voltage power does not immediately disappear from the wafer 2 immediately after the DC high voltage power supply 10 stops the application of the DC high voltage power is that the surface state (surface roughness) of the lower electrode 3 changes. Due to deterioration over time such as changes in leakage current and leakage current, the removal of the electroadhesive force at the time of dechucking becomes insufficient, resulting in dechucking failure.

  If the diameter of the wafer 2 is up to 200 mm, the area of the lower electrode 3 is relatively small. Therefore, the surface condition and the leakage current value change with time is small, and the deterioration of the residual level of the electroadhesive force is not remarkable and is not a level to consider. However, since the amount of DC voltage applied to the lower electrode 3 is increased by increasing the wafer area by increasing the diameter of the wafer 2 to a diameter of 300 mm, the surface of the lower electrode 3 is electrically damaged by the DC voltage and contacted with the wafer 2. The physical damage due to increases, and the deterioration of the surface state is promoted. In particular, in the method in which the wafer 2 is attracted to the lower electrode 3 using the Coulomb force, the tendency of deterioration is remarkable because the amount of DC voltage applied is larger than the method in which the DC voltage is not applied.

  Further, the promotion of deterioration with time of the lower electrode 3 due to the increase in diameter is not limited to the above. For example, since the bias applied to the wafer 2 increases as the amount of high-frequency power applied to generate the bias increases, the lower electrode 3 is electrically damaged. Further, since it becomes difficult to improve the in-plane uniformity of the surface of the wafer 2 as the diameter increases, it is necessary to stabilize the chamber condition more than ever. Therefore, a large number of processes perform dry cleaning (hereinafter, referred to as waferless dry cleaning) in which the wafer 2 is processed without being placed on the lower electrode 3. As a result, the plasma is directly exposed to the surface of the lower electrode 3, thereby causing electrical and physical damage and promoting deterioration with time.

  As described above, the deterioration of the lower electrode 3 with time is promoted by increasing the diameter, and even with the same dechucking technique, the residual adsorption force is not sufficiently removed, dechucking failure occurs, and the wafer 2 is frequently displaced. FIG. 6 shows a graph of the change over time in the amount of deviation of the wafer. It can be seen that the amount of deviation of the wafer 2 gradually increases after the replacement of the lower electrode 3. Once wafer misalignment occurs, significant downtime occurs, such as wafer recovery, chamber opening, and wafer teaching. In the worst case, wafer cracks also occur.

  As a technique for preventing the wafer from being displaced at the time of dechucking, Patent Document 1 discloses a technique in which a wafer guide is arranged at a critical point around the wafer. In this technique, the position of the wafer is physically corrected by a guide when the wafer is lifted up by lift pins.

As a technique for monitoring / detecting the magnitude of the residual adsorption force, Patent Document 2 discloses a monitoring / detection technique using lift pin stress. In this method, when a wafer is lifted up by lift pins, a stress value applied to the lift pins is detected, and the moving speed of the lift pins is controlled based on the detected value so that wafer displacement does not occur.
JP-A-8-172075 JP-A-11-233601

  However, in the method disclosed in Patent Document 1, as described above, the wafer is likely to come into contact with a member in the chamber such as a focus ring, and foreign matter is generated on the wafer, so that the yield may be reduced. . For example, if a 300 mm wafer comes into contact with the guide and foreign matter is generated 10 mm from the periphery, that alone will reduce the yield by about 13%. In recent years when miniaturization is being promoted along with an increase in diameter, it is impossible to use such a method.

  Further, in the method disclosed in Patent Document 2, when the stress value of the lift pin is actually detected, it is difficult to determine whether the value is within the range of variation or the value actually indicating dechucking failure. Depending on the difference in the back surface structure of the wafer, for example, there is a difference in the oxide film thickness. However, since the insulation capacity is different, the residual electroadhesive force is different and the stress value is changed. Further, the stress value also changes depending on the surface condition of the lower electrode and the change in leakage current with time. Therefore, even though it is possible to monitor the stress value, it is not possible to feed back the value to the control of the moving speed of the lift pin.

  Other detection methods for wafer misalignment include changes in the leakage flow rate / pressure of backside gas during dechucking and the leakage current value of the lower electrode. However, this is not the purpose of monitoring the wafer shift at the time of dechucking, but the purpose of monitoring the temporal change of the lower electrode. Since the wafer shift is indirectly monitored using parameters, the detection sensitivity is low. For example, even if it is detected by an abnormal backside gas leakage flow rate / pressure value, it cannot be determined whether the residual electroadsorptive force is changing or whether the backside gas flow rate / pressure itself is changing. It cannot be determined whether wafer misalignment has occurred.

  Furthermore, even if there is a change in the value, as described above, it is difficult to determine whether the value actually indicates a dechucking defect even if monitoring over time. The same applies to the monitoring of the leakage current value of the lower electrode. Therefore, at present, it is almost impossible to detect wafer deviation. For this reason, a method for directly monitoring and detecting wafer misalignment is required.

  The present invention is directed to solving these problems in the prior art, and even when a wafer shift occurs in the chamber processing chamber in the plasma apparatus used in the manufacturing process of the semiconductor device, An object of the present invention is to provide a method of manufacturing a semiconductor device that can detect and correct it.

  In order to achieve the above object, a method of manufacturing a semiconductor device according to the present invention includes a carrying-in step of installing a semiconductor substrate on a stage by an arm, a step of fixing the semiconductor substrate to the stage, and performing a plasma treatment on the semiconductor substrate. A step, a step of releasing the fixation of the plasma-treated semiconductor substrate to the stage, a step of detecting the position of the plasma-treated semiconductor substrate, and an unloading step of transporting the plasma-treated semiconductor substrate from the stage by the arm, In the position detection step, the position of the semiconductor substrate is measured by an optical sensor, and the movement of the arm in the unloading step is controlled based on the position of the semiconductor substrate measured in the position detection step.

  According to a second aspect of the present invention, there is provided a method of manufacturing a semiconductor device, wherein the optical sensor is a CCD (Charge Coupled Device) in the above-described manufacturing method, and the optical sensor is on the circumference of the first radius. A plurality of elements are arranged on the circumference of a second radius concentric with the first radius, and the optical sensor detects a notch portion of the semiconductor substrate.

  According to a fifth aspect of the present invention, there is provided a semiconductor device manufacturing apparatus comprising: a chamber for performing plasma processing; a stage in the chamber; a top plate for covering the upper portion of the chamber; a high-frequency generation source located above the top plate; On a stage disposed on the top plate, including a gas introduction unit and an exhaust unit connected to each other, a spare chamber connected to the chamber via a gate valve, and an arm for moving the wafer between the spare chamber and the chamber. And an optical sensor for detecting the wafer state, and a feedback system for processing information detected by the optical sensor to control the arm.

  According to the above method and apparatus, by using a plurality of optical sensors such as a CCD provided on the top plate in the chamber, the deviation of the vicinity of the edge portion of the semiconductor substrate (wafer), the notch portion, and the deviation direction are confirmed and monitored. Since the output result is fed back to the arm control, even when the wafer is deviated during dechucking, the amount of deviation can be corrected to carry the wafer.

  According to the present invention, there is provided a semiconductor device manufacturing apparatus having a mechanism capable of checking and monitoring a wafer shift amount and shift direction using an optical sensor, and including a system capable of feeding back an output result to a transfer arm. According to the above, even if the wafer is deviated during dechucking, the amount of deviation can be corrected and the wafer can be safely conveyed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram showing a schematic configuration of a plasma processing apparatus in a first embodiment of the present invention. A plasma processing apparatus 200 according to the first embodiment will be described with reference to FIG. Here, in the plasma processing apparatus 200 of the present embodiment, components having equivalent functions corresponding to the constituent elements described in the plasma processing apparatus 100 of FIG. The overlapping description is omitted.

  In this embodiment, the infrared sensor 16 as an optical sensor is concentrically formed with a first radius above the edge portion of the wafer 2 on the lower electrode 3 of the plasma processing apparatus 200 so as to face the lower electrode 3. Three are placed in The infrared sensor 16 is installed so as to be able to detect a point 0.5 mm away from the edge portion of the wafer 2 that is centered and placed on the lower electrode 3 (see FIG. 2).

  Next, the plasma processing method in the first embodiment will be described. In the chamber processing chamber 1, first, the wafer 2 is transferred by the transfer arm 42 and placed on the lower electrode 3. Then, the wafer 2 is adsorbed to the lower electrode 3 and plasma processing is performed. After the processing is completed, the wafer 2 is dechucked, and then the position of the wafer 2 is confirmed by the infrared sensor 16. At that time, when the infrared sensor 16 reacts, it is detected that the wafer is displaced in the reacting direction.

  The transfer accuracy of the transfer arm 42 is 0.2 mm on one side, and the infrared sensor 16 is disposed at a location of 0.5 mm. Therefore, a wafer shift of 0.3 mm or more occurs in the direction in which the infrared sensor 16 is disposed. Can be detected. When the wafer deviation is detected, the wafer position feedback system 44 feeds back the deviation direction and the deviation amount to the transfer arm 42. In this state, the transfer arm 42 is inserted into the chamber processing chamber 1 and the wafer 2 is unloaded. By doing so, it becomes possible to safely carry out the wafer 2 in a state where there is no wafer displacement.

  In the present embodiment, the number of infrared sensors 16 is three. However, when the number of infrared sensors 16 is increased to four or five, the detection accuracy of positional deviation can be further increased.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. As shown in FIG. 3, three infrared sensors 17 having a second radius are arranged outside the concentric outer side of the installed infrared sensor 16. The infrared sensor 17 is installed so as to detect a location 1.0 mm away from the edge portion of the wafer 2 centered on the lower electrode 3. Then, the amount of deviation can be divided into a deviation of 0.5 to 1.0 mm and a deviation of 1.0 mm or more. Therefore, it is possible to divide the amount fed back to the transfer arm 42 into two stages, and more accurately. It becomes possible to correct the wafer misalignment.

  In the present embodiment, three infrared sensors 16 and 17 are provided. However, if the number of infrared sensors 16 and 17 is increased to four or five, the alignment accuracy can be further increased. In FIG. 3, the infrared sensor 17 is disposed outside the infrared sensor 16. However, the infrared sensor 17 may be disposed outside the concentric circle at a position shifted from the infrared sensor 16.

(Third embodiment)
Next, a third embodiment of the present invention will be described. In this embodiment, the sensor to be installed is changed from an infrared sensor to a CCD sensor. Accordingly, since line detection is possible instead of point detection, it is possible to detect the shift amount / shift direction with a line instead of a point. Therefore, it is possible to feed back more accurately to the transfer arm. Further, since it becomes possible to monitor the amount of deviation / direction of deviation over time, it becomes possible to check the reproducibility of wafer deviation.

(Fourth embodiment)
Finally, a fourth embodiment of the present invention will be described with reference to FIG. In the present embodiment, the sensor to be installed is the CCD sensor 18 and is installed above the notch portion of the wafer 2 so that the notch portion of the wafer 2 can be monitored. By monitoring the shift amount / shift direction of the notch portion of the wafer 2 as described above, it is possible to detect not only the shift in the XY direction but also the shift in the rotational direction. When the rotation direction deviation is detected, the wafer 2 is transferred to a wafer rotation mechanism (not shown) such as an orienter by the transfer arm, and the rotation direction deviation can be corrected.

  The above contents can be applied to all plasma processing apparatuses including a mounting table (stage) that holds an object to be processed (wafer) by electrostatic adsorption. Moreover, you may install the light source which illuminates a process chamber with a sensor through all the embodiments.

  According to the semiconductor device manufacturing method and the manufacturing apparatus of the present invention, even when the wafer to be processed (wafer) is dechucked in the chamber processing chamber due to a dechuck defect, the position where the wafer is placed on the transfer arm is corrected to correct the transfer shift or The wafer can be safely transported without cracking the wafer, and is useful as a semiconductor device manufacturing method and apparatus.

The figure which shows schematic structure of the plasma processing apparatus in the 1st Embodiment of this invention. The figure which shows arrangement | positioning of the infrared sensor in 1st Embodiment. The figure which shows arrangement | positioning of the infrared sensor in 2nd Embodiment. The figure which shows arrangement | positioning of the CCD sensor in 4th Embodiment. The figure which shows schematic structure of the conventional plasma processing apparatus Graph showing the change over time in wafer misalignment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Chamber processing chamber 2 Wafer 3 Lower electrode 4, 7 High frequency power supply 5 Outer peripheral ring 6 for confining plasma disposed on the outer periphery of the lower electrode 6 Upper electrode 8 Exhaust part 9 Gas introduction part 10 DC high voltage power supply 11 Backside gas introduction path 12 Backside gas supply device 13 Backside gas pressure measuring device 15 Lift pins 16, 17 Infrared sensor 18 CCD sensor 21 Top plate 41 Chamber preliminary chamber 42 Transfer arm 43 Gate valve 44 Wafer position feedback system 100, 200 Plasma processing apparatus

Claims (5)

Carrying-in process of installing a semiconductor substrate on a stage by an arm;
Fixing the semiconductor substrate to the stage;
Applying a plasma treatment to the semiconductor substrate;
Releasing the fixation of the plasma-treated semiconductor substrate to the stage;
Detecting the position of the plasma-treated semiconductor substrate;
Carrying out the plasma-treated semiconductor substrate from the stage by the arm, and
In the position detection step, the position of the semiconductor substrate is measured by an optical sensor, and the movement of the arm in the unloading step is controlled based on the position of the semiconductor substrate measured in the position detection step. A method for manufacturing a semiconductor device.   2. The method of manufacturing a semiconductor device according to claim 1, wherein the optical sensor is a CCD (Charge Coupled Device).   2. The plurality of optical sensors are arranged on a circumference of a first radius, and further, a plurality of the optical sensors are arranged on a circumference of a second radius concentric with the first radius. Or the manufacturing method of the semiconductor device of 2.   3. The method of manufacturing a semiconductor device according to claim 1, wherein the optical sensor detects a notch portion of the semiconductor substrate. A chamber for plasma treatment;
A stage in the chamber;
A top plate that covers the top of the chamber;
A high-frequency generation source located above the top plate;
A gas inlet and an exhaust connected to the chamber;
A spare chamber connected to the chamber via a gate valve;
An arm for moving the wafer between the preliminary chamber and the chamber;
An optical sensor for detecting a wafer state on the stage disposed on the top plate, and a feedback system for processing detection information of the optical sensor to control the arm. Manufacturing equipment.

Images