JP2008258375A - Plasma damage detection measuring apparatus and plasma processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma damage detecting device or the like capable of obtaining an accurately evaluation. <P>SOLUTION: A substrate wafer is prepared, an insulating film simulated as a gate oxide film is formed on its surface, and a measuring electrode 102 for measuring an electrical potential applied on the insulating film is provided to make the wafer 101 for the measurement. This is mounted in a processing chamber of a plasma processing device, the charge of the measuring electrode 102 is taken out to an output equipment 305 through a high-impedance split probe 104 and an atmosphere side high-voltage probe 304, a charge-up state of the wafer 101 is observed by a monitor of the atmosphere side output equipment 305, and the data can be measured. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus used for manufacturing a semiconductor, and more particularly to a plasma damage detection measuring apparatus and a plasma processing apparatus for detecting and measuring plasma damage in a plasma processing apparatus.

  With the recent miniaturization and high integration of semiconductor devices, it has become an important issue to evaluate the charge charged up on the wafer surface in the chamber during plasma etching during the manufacture of semiconductor devices. This is because the gate oxide film thickness of a semiconductor device becomes thinner with miniaturization and higher integration, so that the voltage that the film can withstand, that is, the withstand voltage gradually decreases, and therefore the withstand voltage can be managed. This is because it becomes important.

  Since the plasma used for etching is generated by high frequency power at this time, when the wafer is exposed to the plasma, it is necessary to consider not only the influence from the plasma but also the influence of the electric field due to the high frequency. As a first conventional technique, an electrical element such as a capacitor, a resistor, an inductor, and a diode is provided under an electrode for applying a high-frequency voltage, and a chip simulating a gate oxide film is embedded on the electrode surface, Thus, a method for measuring the voltage and current applied to the chip, and the amount of charge passing through the gate oxide film at this time has been proposed.

  Next, in the second prior art, a light emitting element / electric element is used to form a detection circuit on the wafer surface, and an element that emits light by utilizing a potential difference generated according to a difference in the inflow amount of charged particles. A method has been proposed for measuring the light emission intensity of the wafer and measuring the potential on the wafer surface.

  On the other hand, there is an evaluation method called TEG (Test Element Group) as a third conventional technique widely used as an evaluation method of charge-up damage due to plasma of this gate oxide film. In this method, first, gate oxidation is performed. Using a wafer consisting of multiple chips with antennas connected to the membrane, plasma processing was performed under the same recipe conditions as the actual device creation, and it is estimated that the plasma processing would have resulted in damage. A gate oxide film is obtained.

  Next, a voltage was gradually applied from a low voltage to the gate oxide film thus obtained until dielectric breakdown appeared, and the voltage value V and the current value I at this time were measured and obtained. A so-called CVS method (Constant Voltage Stress), which evaluates the deterioration level of the film from the IV characteristics, is applied, and as a result, the charge-up damage due to the plasma of the gate oxide film is evaluated.

  The prior art described above has a problem that it cannot be said that the cost required for evaluation is taken into consideration, and is limited in application.

  That is, in the case of the first prior art, since the electrode structure is different from that of the lower electrode when the device is actually fabricated, the atmosphere in the chamber in which the plasma is generated is changed. The voltage value applied to the device wafer will be different, so it is important to correctly grasp the amount of charge passing through the gate oxide film in the actual device using the chamber for developing the device. This is difficult with the first prior art.

  Next, in the case of the second prior art, it is necessary to configure a complicated circuit using an electric element, and at this time, it is necessary to take into consideration the destruction of the element due to high frequency, Difficult and there are problems with accuracy.

  In the third prior art based on the TEG evaluation method described above, once the wafer is exposed to plasma and the degree of deterioration is measured by the CVS method, the wafer cannot be used again. High-cost wafers are required, which limits the application from the viewpoint of profitability.

  Therefore, an object of the present invention is to provide a plasma damage detection apparatus and a plasma damage measurement apparatus that can suppress the cost for evaluating the charge-up damage due to the plasma of the gate oxide film and can obtain an accurate evaluation. It is to provide a plasma processing apparatus using the same.

  In the present invention, in order to measure the potential applied to the wafer, a thin film electrode is provided on the measurement wafer, the state of the wafer being charged up by this electrode is observed, and further automatically controlled. To be achieved.

  For this reason, in the present invention, a thin film measurement electrode is incorporated into a wafer as a voltage probe corresponding to a high frequency for plasma generation, and is loaded into a plasma generation apparatus for producing a product device, and a recipe according to production conditions of an actual device Under this condition, an output monitor outside the atmosphere is used to monitor the state of charging up on the wafer. Furthermore, the waveform and numerical result obtained by the monitoring at this time are used for the recipe for the next processing. The conditions will be changed.

  Therefore, according to the first means, the object is to create an insulating film imitating a gate oxide film on the surface of the fabric wafer and to measure the potential applied to the insulating film. As described above, this is achieved by depositing a conductive film on the insulating film to form a measurement wafer as a measurement electrode, and placing it in a plasma processing apparatus to detect and measure the potential.

  At this time, at least two of the electrodes may be formed on the measurement wafer, and the electrodes are electrically insulated from resistance elements such as a resistor, a coil, and a capacitor in order to protect from high-frequency plasma. The probe may include an insulated and shielded lead wire, and the electric potential may be taken out to the atmosphere side through the probe. Further, at this time, the electrode includes an antenna, and the electric potential is The electrode may be transmitted by radio waves and taken out to the atmosphere side.

  Similarly, the above object can be achieved even if the plasma damage detection / measurement apparatus according to any one of claims 1 to 4 is provided and the plasma is controlled in accordance with the detection / measurement result of the plasma damage.

  At this time, a monitor means for displaying a charge-up waveform and a database for storing information including at least a charge-up reduction condition are provided, and the plasma damage detection and measurement process by the plasma damage detection and measurement apparatus is preset. It may be repeated until the ΔVdc set value is obtained.

  According to the present invention, the directivity of the potential and current distributed on the film to be processed and the gate oxidation can be obtained using a simple potential / current measuring element without greatly changing the configuration of the plasma generation apparatus used for device creation. Since the amount of charge passing through the membrane can be easily measured and grasped, it is possible to provide a measurement system and apparatus system effective for reducing charge-up damage.

  In addition, according to the present invention, charging damage that can measure current, potential, and amount of charge flowing non-uniformly on the wafer top surface due to charge-up and can be monitored in real time in a commercial plasma generator. A measurement system and a charging damage reduction apparatus system can be provided.

  Hereinafter, a plasma damage detection apparatus, a plasma damage measurement apparatus, and a plasma processing apparatus according to the present invention will be described in detail with reference to the illustrated embodiments.

-Embodiment 1
FIG. 1 is a schematic view showing an embodiment of the present invention in which a measurement electrode and a measurement probe are installed on a measurement wafer to form a plasma damage detection device and a plasma damage measurement device. (Bare Silicon Wafer) is prepared, and an insulating film that simulates a gate oxide film is formed on the surface of the wafer 101 as a measurement wafer 101, and an electrode for measuring the potential applied to the insulating film As described above, a conductive film such as an aluminum tape is deposited on the insulating film.

  Here, at the time of production, a film having a certain size and the same area is produced so that the potential generated on the wafer surface is unified with that caused by the influence of plasma. Then, the outer peripheral portion is shielded with an insulating film, and the measurement electrode 102 is formed so as to suppress the tear of the simulated oxide film due to anisotropic etching. Then, as a high-impedance split probe 104 attached to the measurement electrode 102, an electrical element such as a coil or a capacitor for cutting off a high frequency supplied from a power source is connected, and the wafer surface by plasma applied to the measurement electrode A resistance element having a size in consideration of the above potential is connected.

  At this time, these electrical elements and the lead wire 103 are completely covered with an insulator so that the electrical elements in the probe can be prevented from being affected by the bias power source and the potential being generated. This will be further described with reference to FIG. Here, FIG. 2 simply shows a cross-sectional view of the measurement electrode and a state in which the high-impedance split probe is connected. First, as shown in FIG. 2, an oxide system simulating a gate oxide film is used. The insulating film 201 is provided at two or more points on the wafer where the plasma is unevenly distributed in consideration of the film thickness and area. Then, a thin film 202 having a controlled size (area) and conductivity is deposited immediately above.

  Then, the amount of charge passing per unit time can be calculated from the area of the conductive thin film 202 at this time. Therefore, next, at least two measurement electrodes 102 are formed by covering the outer peripheral portion with an insulating film. Then, the tip of the high-impedance split probe 104, which is the same material as the conductive thin film, is attached so that the plasma is uniformly applied to the conductive thin film 202.

  Next, FIG. 3 simply shows the situation from when the wafer 101 and the high-impedance split probe 104 connected to the measurement electrode 102 are placed in the vacuum processing chamber to the output device 305 on the atmosphere side. Here, a state is shown in which an impedance dividing circuit 301 is provided in order to avoid a large current from plasma flowing into the output device 305 at once.

  Therefore, the current due to the potential of the measurement electrode 102 is converted into a voltage divided by the impedance dividing circuit 301 and supplied to the high voltage measurement probe 304 outside the plasma generation processing apparatus via the core wire 302 of the shield cable 304. Here, the voltage is further divided and taken into the output device 305. At this time, as shown in the figure, the probe 304 is shielded in consideration of the influence of high-frequency power and the influence of large current flow in the vacuum plasma processing apparatus. Here, reference numeral 306 denotes an atmospheric side high voltage probe ground wire.

  In this way, by measuring the potential applied to the gate oxide film using two or more measurement electrodes and probes, the potential received by the measurement electrode alone can be visualized in the output device 305, respectively. The charge passing through the conductive membrane can be calculated. At this time, by taking the difference between the charges, it is possible to grasp the direction of the current generated from the non-uniform plasma and the potential generated between the measurement electrodes. As a result, the gate oxide film is simulated. The charge-up damage of the insulating film can be evaluated.

  Next, the case where the measurement wafer and the measurement probe are incorporated in the processing chamber of the plasma generation processing apparatus will be described with reference to FIG. At this time, the plasma generation processing apparatus includes a plasma generation processing chamber lower cover 404 and a plasma generation processing chamber upper cover 405, and the wafer 101 including the measurement electrode 102 is placed together with the quartz ring 403 therein. At this time, the plasma generation processing apparatus includes a shower plate 406, to which power is supplied from the high frequency power generation apparatus 407 to form a high frequency electric field. As a result, plasma 401 is generated. At this time, in order to attract charged particles from the plasma, a high frequency voltage is applied from the high frequency power generator 409 to the lower electrode 402, and due to this, a potential is applied to the measurement electrode 102 on the wafer placed on the lower electrode 402. Is applied. Reference numerals 408 and 410 are grounds.

  The potential that appears as a result of the measurement electrode 102 being affected in this way is a measurement data monitor that can be monitored in real time via the high impedance division probe 104 in vacuum and the high voltage measurement probe 304 in the atmosphere. The output device 305 is connected. Therefore, by changing the setting of the output device 305 at this time, it is possible to know the current difference and directionality between two or more electrodes and the amount of inflowed charge. Therefore, according to this embodiment, the measurement It is possible to evaluate the charge-up damage of the insulating film only by using the wafer for manufacturing.

-Embodiment 2
FIG. 5 shows a plasma damage detection apparatus and a plasma damage measurement apparatus in which a measurement electrode 102 is directly installed on a wafer of a product device in order to verify damage to an oxide film due to charge-up damage in the process of producing a product device. In this case, the processed film 501 to be etched under certain conditions is divided, and the measurement electrode 102 is placed on them. At this time, these measurement electrodes 102 are the same as those described with reference to FIGS.

  Then, the potential obtained by these measurement electrodes 102 is supplied to the external device 305 described with reference to FIG. 3 through the probe 105 described above, and is monitored in the same manner as in the first embodiment. be able to. Here, 502 is an etch stopper layer, and 503 is a film to be processed.

  Next, FIG. 6 shows an equivalent circuit for explaining the measurement operation in the case of FIG. 5 in which measurement electrodes are provided on the wafer of the product device. Here, the capacitances 601 and 602 are respectively shown in the figure. The capacitance Zc1 at this time is obtained by changing the film area of the measurement electrode 102 or the film thickness of the insulating film 201. To play a role.

  On the other hand, the capacitor 603 is formed by a film to be processed 503 sprayed on the surface of the lower electrode, and the electrostatic capacitance Cf due to the capacitor 603 uniformly distributes the charge incident from the plasma over the entire wafer. For this reason, if the electrostatic capacity Zc1 ′ of the capacitor 602 by the other film to be processed 502 has a uniform electrostatic capacity at any point on the wafer, these are Zc1≈Zc1 ′. It is necessary to have a capacitance in the relationship.

  At this time, the ion sheath 604 generated between the plasma and the lower electrode instantaneously holds the flow of charged particles from the plasma to the lower electrode side. Therefore, in the probe 104 connected to the measurement electrode 102 on the wafer, the charged particles It is necessary to consider the transient load. Therefore, it is necessary to provide the blocking capacitor 605 in the probe, and the electrostatic capacity Zp should be overwhelmingly increased as Zp >> Zc2 so that the influence of the electrostatic capacity Zc2 by the ion sheath 604 can be ignored.

-Embodiment 3
FIG. 7 is a schematic view showing an embodiment of the present invention in which a measurement electrode and a measurement probe are installed on a measurement wafer to form a plasma processing apparatus. In this case, the same configuration as the first embodiment is shown. Analyzing the data measured by, and changing the following process conditions, so that charge-up damage reduction can be obtained, this is because the inventors of this case conducted experiments and acquired enormous data Thus, the condition can be automatically determined.

  In FIG. 7, the wafer 101 having the measurement electrode 102 is placed on the plasma generation processing chamber lower cover 404 in the plasma generation processing chamber 701. Therefore, a potential is applied to the measurement electrode 102 by the plasma generated in the plasma generation processing chamber 701. Therefore, this potential is transmitted to the high voltage probe 702 in the lower electrode provided in the plasma generation processing chamber lower cover 404 via the high impedance division probe 104, and taken out from here to the AD signal converter 703 in the atmosphere, This is supplied to the device control monitor 704 and the condition setting database 705.

  The device control monitor 704 displays a charge-up waveform, and the condition setting database 705 stores condition setting data including charge-up decreasing condition information. Therefore, based on the waveform displayed on the device control monitor 704, the operator inputs a condition and executes processing, and the information is transmitted from the setting condition loading unit 706 to the buffer processing unit 708 via the control processing controller 707. Is done.

  Therefore, plasma processing conditions are set based on the buffered information, and the plasma processing is operated based on the set plasma processing conditions. Then, the setting of the plasma processing conditions and the operation of the plasma processing based on the set plasma processing conditions are such that the detected charge is reduced by the charge-up damage, and it is set in advance as a voltage that is allowed. Repeat until the set value is reached.

  Therefore, according to this embodiment, the state of the plasma is automatically controlled in a direction in which the charge-up damage is reduced, and as a result, damage control is performed on the gate oxide film, which is highly reliable. A plasma processing apparatus that contributes to the manufacture of semiconductor devices is obtained.

  At this time, it is also possible to automatically control the charge-up damage from the obtained result. In this case, the control processing controller 707 is based on the data input to the condition setting database 705. Charge up by calculating conditions, calculating optimum conditions, feeding back the information to the plasma generation processing chamber 701 via the buffer processing unit 708, and processing based on the fed back process conditions. It is possible to generate a plasma with less.

-Embodiment 4
Next, as a fourth embodiment of the present invention, a plasma processing apparatus in which a decrease in charge-up damage is automatically obtained without using a probe, so-called probeless, will be described with reference to FIG. In this case, as shown in the drawing, a measurement wafer 801 is disposed in the plasma generation processing chamber 701. The potential on the wafer surface can be blown to the measurement wafer 801 by radio frequency electromagnetic waves. A measurement electrode 802 with an antenna is formed.

  The electromagnetic wave transmitted from the measurement electrode 802 with the antenna is received by the voltage signal passive element 803 installed in the plasma generation processing chamber 701 and is then supplied to the AD signal converter 703, from which the apparatus control monitor 704 and the condition setting database 705. Hence, processing is performed with the same configuration as that of the embodiment described with reference to FIG.

  That is, the device control monitor 704 displays a charge-up waveform, and the condition setting database 705 stores condition setting data including charge-up decreasing condition information. Therefore, based on the waveform displayed on the device control monitor 704, the operator inputs a condition to execute processing. Then, the information is transmitted from the setting condition loading unit 706 to the buffer processing unit 708 via the control processing controller 707. Therefore, plasma processing conditions are set based on the buffered information, and the plasma processing is operated based on the set plasma processing conditions.

  Then, the setting of the plasma processing conditions and the operation of the plasma processing based on the set plasma processing conditions are repeated until a δVdc set value at which damage is reduced is obtained. As a result, a plasma processing apparatus that contributes to the manufacture of a semiconductor device with high reliability can be obtained. However, in this embodiment, no probe is required, and accordingly, the configuration is accordingly increased. Becomes easier.

  Also in this embodiment, it is possible to automatically control the charge-up damage from the obtained result. In this case, the control process is performed based on the data input to the condition setting database 705. The controller 707 determines the conditions, calculates the optimum conditions, feeds back the information to the plasma generation processing chamber 701 via the buffer processing unit 708, and processes based on the fed back process conditions. Plasma with little charge-up can be generated.

It is explanatory drawing which shows an example of measurement electrode arrangement | positioning in embodiment of the plasma damage detection apparatus and plasma damage measurement apparatus by this invention. It is sectional drawing of the measurement electrode in one Embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing of the whole in embodiment of the plasma damage detection apparatus and plasma damage measurement apparatus by this invention. It is explanatory drawing at the time of installing the plasma damage detection apparatus and plasma damage measurement apparatus by this invention in a plasma processing chamber. It is sectional drawing of the measurement electrode in other one Embodiment of this invention. It is the equivalent circuit schematic of one Embodiment of the plasma damage detection apparatus and plasma damage measurement apparatus by this invention. It is explanatory drawing which shows one Embodiment of the plasma processing apparatus by this invention. It is explanatory drawing which shows other one Embodiment of the plasma processing apparatus by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101: Wafer 102: Measuring electrode 103: High impedance division | segmentation probe lead wire 104: High impedance division | segmentation probe 201: Insulating film 202: Conductive thin film 203: Insulating film for shielding 301: Impedance dividing circuit 302: Core wire (core wire of a shield cable)
303: Shielded cable 304: Atmospheric side high voltage probe 305: Output device (measurement data monitor)
306: Atmospheric side high voltage probe ground wire 401: Plasma generated in plasma generator 402: Lower electrode 403: Quartz ring 404: Plasma generation processing chamber lower cover 405: Plasma generation processing chamber upper cover 406: Shower plate 407: High frequency generating power source 408: Ground 409: High-frequency power generation 410: Ground 501: Film to be processed 502: Etch stop 503: Film to be processed 604: Ion sheath 605: High voltage split probe 701: Plasma generation processing chamber 702: High voltage probe in the lower electrode 703 : AD signal converter 704: Device control monitor 705: Condition setting database 706: Setting condition load unit 707: Control processing controller 708: Buffer processing unit 801: Wafer 802: Measuring electrode with antenna 803: Voltage signal passive element

Claims (6)

  An insulating film imitating a gate oxide film is created on the surface of the fabric wafer, and a conductive film is deposited on the insulating film as an electrode for measuring the potential applied to the insulating film. A plasma damage detection / measurement apparatus comprising: a measurement wafer serving as a measurement electrode; and the wafer is placed in a processing chamber of the plasma processing apparatus to detect and measure the potential. In the plasma damage detection and measurement apparatus according to claim 1,
A plasma damage detection / measurement apparatus, wherein at least two electrodes are formed on the measurement wafer. In the plasma damage detection and measurement apparatus according to claim 1 or 2,
The electrode includes a probe composed of an insulated and shielded lead wire and an electrical element such as a resistor, a coil, and a capacitor insulated to protect against high-frequency plasma,
The plasma damage detection and measurement apparatus, wherein the potential is taken out to the atmosphere side through the probe. In the plasma damage detection and measurement apparatus according to claim 1 or 2,
The electrode includes an antenna that transmits the electric charge of the electrode as a radio frequency electromagnetic wave,
The plasma damage detection and measurement apparatus, wherein the potential is taken out to the atmosphere side through the antenna and a voltage signal passive element installed in the processing chamber.   5. The plasma damage detection and measurement apparatus according to claim 1, wherein the plasma in the processing chamber is controlled in accordance with a result of detection and measurement of plasma damage by the plasma damage detection and measurement apparatus. A plasma processing apparatus. The plasma processing apparatus according to claim 5, wherein
A monitor means for displaying a charge-up waveform, and a database for storing information including at least a charge-up reduction condition;
A plasma processing apparatus, wherein the plasma damage detection and measurement process by the plasma damage detection and measurement apparatus is repeated until a preset ΔVdc set value is obtained.

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