JP4963023B2 - Sputtering method and sputtering apparatus - Google Patents

Description

  The present invention relates to a sputtering method and a sputtering apparatus that enable film formation on the surface of a processing substrate.

  In the sputtering method, ions in a plasma atmosphere are accelerated and bombarded toward a target formed in a predetermined shape according to the composition of a thin film to be formed on the surface of the processing substrate, and target atoms are scattered, thereby processing the substrate. A thin film is formed on the surface. In this case, a plasma atmosphere is formed by applying a voltage to the target, which is a cathode electrode, via a DC power supply or an AC power supply, thereby generating a glow discharge between the cathode electrode and the anode electrode or the earth electrode. .

  During such glow discharge, it is known that arc discharge occurs for some reason, and if this arc discharge occurs locally at the cathode electrode, problems such as generation of particles and splash are induced, which is good. Film formation is impossible.

Therefore, in the sputtering method using a DC power source, for example, the voltage between the cathode electrode and the earth electrode is detected, and when the amount of voltage drop exceeds a predetermined value, the occurrence of arc discharge is detected, and the arc discharge is detected. There is known one in which power supply is cut off from a DC power source within a predetermined time after occurrence of discharge (Patent Document 1)
Japanese Patent Laid-Open No. 11-200036 (for example, refer to claim 1).

  However, sputtering using an AC power source, that is, a voltage is applied to a pair of targets arranged in a floating state in a vacuum chamber by alternately changing the polarity at a predetermined frequency via the AC power source, and each target is an anode. In the case of sputtering by alternately switching between the electrode and the cathode electrode, the polarity of the voltage applied to each target constantly changes, and in addition, a voltage drop occurs every time, so the voltage drop between the cathode electrode and the anode electrode It was difficult to apply the arc detection method based on the detection of.

  In this case, conventionally, it has been considered that the effective value or average value of the output voltage from the AC power source to the target is obtained and the output voltage is converted to DC, and arc detection is performed based on the DC voltage. Since the time required for changing to the DC voltage is added, there is a problem in that the detection of the occurrence of arc discharge is delayed, and the generation of particles and splash cannot be effectively prevented.

  Therefore, in view of the above points, an object of the present invention is to quickly detect the occurrence of arc discharge and shut off the output to the target when forming a film by sputtering using an AC power source, and to reduce the energy at the time of arc discharge occurrence. It is an object of the present invention to provide a sputtering method and a sputtering apparatus which can be reduced to effectively prevent generation of particles and splashes.

In order to solve the above-described problem, the sputtering method according to claim 1 applies a voltage to a pair of targets provided in a vacuum chamber by alternately changing the polarity at a predetermined frequency via an AC power source. Is a sputtering method of alternately switching between an anode electrode and a cathode electrode, generating a glow discharge between the anode electrode and the cathode electrode to form a plasma atmosphere, and sputtering each target, wherein output voltage waveforms to the pair of targets When the voltage drop time of the output voltage is determined to be shorter than that during normal glow discharge, the output from the AC power supply is cut off.

  According to the present invention, when a voltage is applied to a pair of targets via an AC power source, each target is alternately switched between an anode electrode and a cathode electrode, and a glow discharge is generated between the anode electrode and the cathode electrode to form a plasma atmosphere. Then, ions in the plasma atmosphere are accelerated and bombarded toward the target serving as the cathode electrode, and the target atoms are scattered to form a thin film on the surface of the processing substrate.

When arc discharge occurs during sputtering, the impedance of the plasma rapidly decreases, and the voltage between the targets first decreases, and a large current flows accordingly. In this case, in order to directly detect the occurrence of arc discharge from the length of the voltage drop time of the output voltage waveform to the target, the change in the current value between the targets and the effective value or average value of the output voltage to the target are obtained to determine the arc discharge. Compared with a device that detects discharge, it is possible to quickly detect the occurrence of arc discharge and shut off the output to the target. As a result, it is possible to effectively prevent the generation of particles and splash by reducing the energy when arc discharge occurs. In the present invention, the “output voltage waveform” means a waveform of a potential difference between the targets when AC power is supplied from the AC power source to the pair of targets. Further, “voltage drop” means that the potential difference between the targets becomes small, and “voltage drop time” means the time required for the potential difference to become small to a predetermined value.

In this case, it detects the output current waveform between said pair of targets mutually the absolute value of the output current exceeds a predetermined value, it is considered that the glow discharge occurs, a current gate from the absolute value of the output current with make signals, create a voltage pulse signal from the absolute value of the output voltage, when the voltage pulse signal in the on state of the current gate signal is turned off, when the voltage drop time is normal glow discharge of the output voltage What is necessary is just to judge that it is a short time. According to this, since the occurrence of a voltage drop is detected when a current flows between the targets, for example, erroneous detection of arc discharge can be reduced. In the present invention, “absolute value” means an absolute value of a value indicated by an arbitrary waveform. For example, “absolute value of output voltage” means the absolute value of the voltage indicated by the waveform of the output voltage, that is, the absolute value of output voltage value, and “absolute value of the output current” means the current indicated by the waveform of output current. Of the output current, that is, the absolute value of the output current value.

  In order to detect the occurrence of arc discharge with higher accuracy, it is preferable to control so that the phases of the output current waveform and the output voltage waveform to the target substantially coincide during the sputtering.

  In this case, it is preferable to change the predetermined value according to the input power from the AC power source to the pair of targets.

Further, the making the voltage pulse signal from the absolute value of the output voltage, and detects the pulse width of the voltage pulse signal, when the pulse width is smaller than the predetermined value, the voltage drop time of the output voltage It may be determined that the time is shorter than that during normal glow discharge. According to this, since the occurrence of arc discharge can be detected only by the voltage between the targets, there is no need to consider the phase shift between the output voltage waveform and the output current waveform, and the output voltage waveform and the output current waveform such as at startup Even when the phases do not match, the occurrence of arc discharge can be detected.

In this case, the predetermined value, either determined directly from the absolute value of the output voltage, or the pulse width in the case of not generating the arc discharge may be previously measured and determined relative.

Further, to detect a differential waveform which is proportional to the voltage drop of the output voltage, when the absolute value of the differential value is greater than a predetermined value, when the voltage drop time is normal glow discharge of the output voltage waveform It may be determined that the time is shorter. According to this, since the arc discharge detection circuit can be realized with a simple circuit configuration, and the occurrence of arc discharge is detected only by the voltage between the targets, the phase shift between the output voltage waveform and the output current waveform is prevented. There is no need to consider it, and it is possible to detect the occurrence of arc discharge even when the phase of the output voltage waveform and the output current waveform do not match, such as during startup.

  In this case, in order to detect the occurrence of arc discharge with higher accuracy, it is preferable to remove noise in the output voltage waveform through a filter circuit prior to detecting the differential waveform.

  The output voltage waveform is preferably a substantially sine wave.

Further, an output current waveform between the pair of targets is detected, and after adjusting the phase and amplitude of the output voltage waveform and the output current waveform to substantially coincide with each other, a differential waveform of these waveforms is detected, and this difference is detected. When the absolute value of the value exceeds a predetermined value, the voltage drop time of the output voltage waveform may be determined to be shorter than that during normal glow discharge. According to this, the waveform used for arc detection is synthesized from the difference between the appropriately adjusted current waveform and voltage waveform, so that when the arc discharge occurs, the output of the difference waveform is larger. Since it becomes a waveform, it is difficult to be affected by noise, and as a result, false detection can be reduced.

  In this case, in order to detect the occurrence of arc discharge with higher accuracy, it is preferable to remove noise of the output voltage waveform and the output current waveform through a filter circuit prior to detecting the differential waveform.

  The output voltage waveform and output current waveform are preferably substantially sine waves.

In order to solve the above-mentioned problem, a sputtering apparatus according to claim 13 applies a voltage between a pair of targets provided in a vacuum chamber and a polarity between the pair of targets alternately at a predetermined frequency. a AC power supply to the arc detection means for voltage drop time of the output voltage to the target to detect a voltage drop which is faster than the normal glow discharge, from the AC power supply output from the arc detection circuit And a shut-off means for shutting off the output.

  In this case, the AC power supply may be provided with phase adjusting means for substantially matching the phases of the output voltage waveform and the output current waveform to the pair of targets.

The arc detection means includes a first absolute value detection circuit and a second absolute value detection circuit for detecting an absolute value of an output current and an output voltage between the pair of targets, and a first absolute value detection circuit and a second absolute value. A current gate signal generation circuit and a voltage pulse signal generation circuit provided with a comparator to which an absolute value and a detection level from the detection circuit are respectively input, and a current gate signal and a voltage from the current gate signal generation circuit and the voltage pulse signal generation circuit When the voltage gate signal is turned off when the current gate signal is on, the voltage drop is detected for a shorter time than during normal glow discharge. Is.

Further, the arc detection means other forms, the absolute value detection circuit for detecting the absolute value of the output voltage between said pair of targets mutually voltage waveform and the detection level from the absolute value detecting circuit is inputted compared A voltage pulse generation circuit provided with a voltage detector and a voltage drop detection circuit to which a voltage pulse signal from the voltage pulse generation circuit is input, and detects the pulse width of the voltage pulse signal input to the voltage drop detection circuit, When this pulse width becomes smaller than a predetermined value, a voltage drop that is shorter than that during normal glow discharge is detected.

Further, the arc detection means other forms, the arc detection means includes a differentiating circuit for detecting a differential waveform which is proportional to the voltage drop of the output voltage between said pair of targets mutually differential value in the differential circuit An absolute value detection circuit for detecting an absolute value and a voltage differential waveform circuit having a comparator to which the absolute value from the absolute value detection circuit and a detection level are input. The absolute value of the differential value exceeds a predetermined value. In this case, a voltage drop that is shorter than a normal glow discharge is detected.

Further, the arc detection means of another form includes first and second gain adjustment circuits for adjusting the amplitudes of the output voltage waveform and the output current waveform between the pair of targets to substantially coincide with each other, and each gain adjustment. A differential amplifier that detects a difference waveform between an output voltage waveform and an output current waveform from the circuit, an absolute value detection circuit that detects an absolute value of the difference value in the differential amplifier , and a differential waveform from the absolute value detection circuit And a differential waveform detection circuit having a comparator to which a detection level is input, and when the absolute value of the difference value exceeds a predetermined value, the voltage is shorter than that during normal glow discharge. It detects the descent.

  As described above, the sputtering method and sputtering apparatus of the present invention can quickly detect the occurrence of arc discharge and shut off the output to the target even when the film is formed by sputtering using an AC power source. It is possible to effectively prevent the generation of particles and splash by reducing the energy of the.

  Referring to FIG. 1, reference numeral 1 denotes a magnetron sputtering apparatus (hereinafter referred to as “sputtering apparatus”) of the present invention. The sputtering apparatus 1 is of an in-line type, and has a vacuum chamber 11 that can be maintained at a predetermined degree of vacuum via a vacuum exhaust means (not shown) such as a rotary pump or a turbo molecular pump. A substrate transfer means is provided in the upper part of the vacuum chamber 11. This substrate transport means has a known structure, for example, has a carrier 2 on which the process substrate S is mounted, and intermittently drives the drive means to sequentially transport the process substrates S to a position facing a target to be described later. it can.

  A gas introducing means 3 is provided in the vacuum chamber 11. The gas introduction means 3 communicates with a gas source 33 through a gas pipe 32 provided with a mass flow controller 31, and reacts with a sputtering gas such as Ar or a reaction such as O 2, H 2 O, H 2 or N 2 used in reactive sputtering. Gas can be introduced into the vacuum chamber 11 at a constant flow rate. A cathode electrode C is disposed below the vacuum chamber 11.

  The cathode electrode C has a pair of targets 41a and 41b disposed to face the processing substrate S. Each target 41a, 41b is manufactured by a known method according to the composition of a thin film to be formed on the processing substrate S, such as Al, Ti, Mo, or ITO, and is formed in a substantially rectangular parallelepiped (rectangular in a top view). Yes. Each target 41a, 41b is joined to a backing plate 42 for cooling the target 41a, 41b during sputtering through a bonding material such as indium or tin, and is attached to the frame of the cathode electrode C through an insulating material (not shown). In the vacuum chamber 11, it is arranged in a floating state.

  In this case, the targets 41a and 41b are juxtaposed so that the sputtering surfaces 411 when not in use are positioned on the same plane parallel to the processing substrate S, and between the side surfaces 412 facing each of the targets 41a and 41b. Does not have any components such as an anode or a shield. The external dimensions of the targets 41a and 41b are set to be larger than the external dimensions of the processing substrate S when the targets 41a and 41b are arranged side by side.

  Further, the cathode electrode C is equipped with a magnet assembly 5 positioned behind each of the targets 41a and 41b. The magnet assembly 5 includes a support plate 51 provided in parallel with the targets 41a and 41b. The support plate 51 is made of a rectangular flat plate formed so as to extend to both sides of the targets 41a and 41b along the longitudinal direction of the targets 41a and 41b. The support plate 51 amplifies the magnet's adsorption force. Made of magnetic material. On the support plate 51, a bar-shaped central magnet 52 along the longitudinal direction of the targets 41a and 41b and a peripheral magnet 53 provided along the outer periphery of the support plate 51 are provided. In this case, the volume when converted to the same magnetization of the central magnet 52 is, for example, equal to the sum of the volumes when converted to the same magnetization of the peripheral magnet 52 (peripheral magnet: center magnet: peripheral magnet = 1: 2: 1). It is designed to be.

  Thereby, balanced closed-loop tunnel-shaped magnetic fluxes are formed in front of the targets 41a and 41b, respectively, and the ions ionized in front of the targets 41a and 41b and the secondary electrons generated by sputtering are captured. The plasma density can be increased by increasing the electron density in front of each of 41a and 41b. An output cable K from the AC power source E is connected to the pair of targets 41a and 41b, respectively, and a voltage is applied to the pair of targets 41a and 41b with alternating polarity at a predetermined frequency (1 to 400 KHz). it can.

  As shown in FIG. 2, the AC power source E includes an electric power supply unit 6 that can supply electric power, and an oscillation unit 7 that alternately changes polarity at a predetermined frequency and outputs a voltage to each target 41 a and 41 b. Composed. In this case, the waveform of the output voltage is a substantially sine wave, but is not limited thereto, and may be a substantially square wave, for example.

  The power supply unit 6 includes a first CPU circuit 61 that controls its operation, an input unit 62 to which commercial AC power (three-phase AC 200 V or 400 V) is input, and rectifies the input AC power to generate DC power. 6 diodes 63 for converting to DC, and plays a role of outputting DC power to the oscillation unit 7 via the DC power lines 64a and 64b.

  The power supply unit 6 is connected to a switching transistor 65 provided between the DC power lines 64a and 64b and a first CPU circuit 61 so as to be communicable, and controls the on / off of the switching transistor 65. A driver circuit 66a and a first PMW control circuit 66b are provided. In this case, a detection circuit 67a and an AD conversion circuit 67b are provided which have a current detection sensor and a voltage detection transformer and detect the current and voltage between the DC power lines 64a and 64b, and are provided via the detection circuit 67a and the AD conversion circuit 67b. Are input to the CPU circuit 61.

  On the other hand, the oscillating unit 7 includes four second CPU circuits 71 communicably connected to the first CPU circuit 61 and four oscillation switch circuits 72 provided between the DC power lines 64a and 64b. The second to fourth switching transistors 72a, 72b, 72c, 72d are connected to the second CPU circuit 71 in a communicable manner, and control the on / off of the switching transistors 72a, 72b, 72c, 72d. A driver circuit 73a and a second PMW control circuit 73b are provided.

  Then, by the second driver circuit 73a and the second PMW control circuit 73b, for example, on and off timings of the first and fourth switching transistors 72a and 72d and the second and third switching transistors 72b and 72c. When the operations of the switching transistors 72a, 72b, 72c, 72d are controlled so as to be inverted, sinusoidal AC power can be output via the AC power lines 74a, 74b from the oscillation switch circuit 72. In this case, a detection circuit 75a and an AD conversion circuit 75b for detecting an oscillation voltage and an oscillation current are provided, and are input to the second CPU circuit 71 via the detection circuit 75a and the AD conversion circuit 75b.

  The AC power lines 74a and 74b are connected to an output transformer 76 having a known structure via a resonance LC circuit in series or parallel or a combination thereof, and an output cable K from the output transformer 76 is connected to a pair of targets 41a and 41b. Are connected to each. In this case, a detection circuit 77a and an AD conversion circuit 77b are provided, which have a current detection sensor and a voltage detection transformer, and detect an output voltage and an output current to the pair of targets 41a and 41b. To be input to the second CPU circuit 71 via. This makes it possible to apply a constant voltage to the pair of targets 41a and 41b while changing the polarity alternately at a constant frequency via the AC power source E during sputtering.

  The output from the detection circuit 77a is connected to a detection circuit 78a that detects the output phase and frequency of the output voltage and output current, and through an output phase frequency control circuit 78b that is communicably connected to the detection circuit 78a. Thus, the phase and frequency of the output voltage and output current are input to the second CPU circuit 71. Thus, the on / off of each switching transistor 72a, 72b, 72c, 73d of the oscillation switch circuit 72 is controlled by the second driver circuit 73a by the control signal from the second CPU circuit 71, and the output voltage and output current are controlled. The output phase frequency control circuit 78b, the second CPU circuit 71, and the second driver circuit 73a constitute a phase adjusting means.

  Then, the processing substrate S is transferred to a position facing the pair of targets 41 a and 41 b by the substrate transfer means, and a predetermined sputtering gas is introduced through the gas introduction means 3. An AC voltage is applied to the pair of targets 41a and 41b via the AC power source E, and the targets 41a and 41b are alternately switched between the anode electrode and the cathode electrode, and a glow discharge is generated between the anode electrode and the cathode electrode to generate a plasma atmosphere. Form. As a result, ions in the plasma atmosphere are accelerated and bombarded toward one of the targets 41a and 41b that have become cathode electrodes, and target atoms are scattered to form a thin film on the surface of the processing substrate S.

  In this case, the magnet assembly 5 is provided with driving means such as a motor (not shown), and is reciprocated between the two positions along the horizontal direction of the targets 41a and 41b in parallel and at a constant speed by the driving means. In addition, the erosion area is obtained uniformly over the entire surface of the targets 41a and 41b.

By the way, it is known that arc discharge occurs for some reason during the glow discharge. If this arc discharge occurs locally at the pair of targets 41a and 41b, problems such as generation of particles and splash are caused. since the induced satisfactorily to form a thin film, quickly detect the arcing onset production, it is necessary to immediately shut off the output from the AC power supply E.

In the present embodiment, the oscillating unit 7 is provided with arc detecting means 8 for detecting a voltage drop in which the voltage drop time of the output voltage waveform to the pair of targets 41a and 41b is shorter than that during normal glow discharge. It was. When the arc detection means 8 detects the occurrence of arc discharge, the voltage drop arc output signal is output to the second CPU circuit 71 connected to be communicable, and the first CPU communicable with the second CPU circuit 71 is provided. The operation of the switching transistor 65 is controlled by the first driver circuit 66a by the control signal from the circuit 61, and the output to the pair of targets 41a and 41b is immediately cut off. The “output voltage waveform” is an output voltage detected by the output voltage / current detection circuit 77b when AC power is supplied from the AC power source E to the pair of targets 41a and 41b (that is, between the targets 41a and 41b). (Potential difference) waveform. On the other hand, “voltage drop” means that the potential difference between the targets 41a and 41b becomes small, and “voltage drop time” means the time required for the potential difference to become a predetermined value. More specifically, while the potential difference between the targets 41a and 41b repeatedly increases or decreases in the output voltage waveform detected by the output voltage / current detection circuit 77b, the potential difference between the targets 41a and 41b exceeds a predetermined value. It means the change time until the potential difference gradually decreases and returns to a predetermined value after it increases.

  In this case, each switching transistor of the oscillation switch circuit 72 is controlled by the second driver circuit 73a with the control signal from the second CPU circuit 71 so that the potential between the AC power lines 74a and 74b becomes the same, for example. You may control the operation | movement of 72a, 72b, 72c, 72d, and interrupt | block the output to a pair of target 41a, 41b immediately.

As shown in FIGS. 3A to 3E, the arc detection means 8 includes an output voltage from the detection circuit 77a, a current sensor amplifier 81 and a voltage transformer amplifier 82 that amplify the output current, and a current sensor amplifier 81. And a first absolute value detection circuit 83a and a second absolute value detection circuit 83b for detecting the absolute values of the output current and the output voltage amplified by the voltage transformer amplifier 82. Further, the arc detection means 8 includes a comparator 841 to which the absolute values from the first and second absolute value detection circuits 83a and 83b and the preset current gate detection level and voltage pulse detection level are input, respectively. And a voltage drop detection circuit 85 to which a current gate signal and a voltage pulse signal from the current gate generation circuit 84a and the voltage pulse generation circuit 84b are respectively input. In this case, the preset current gate detection level and voltage pulse detection level (predetermined values) are changed according to the output from the power supply unit 6 to the pair of targets 41a and 41b, for example, and the arc is more accurately You may enable it to detect.

  Next, detection of occurrence of arc discharge in the arc detection circuit 8 will be described. First, the switching transistor 65 is controlled by a control signal from the first CPU circuit 61 of the power supply unit 6 and DC power is supplied to the oscillation unit 7 via the DC power lines 64a and 64b. Next, the operation of the first to fourth switching transistors 72 a, 72 b, 72 c, 72 d is controlled by a control signal from the second CPU circuit 71, and an alternating voltage is applied to the pair of targets 41. In this case, the current drop detection circuit 85 is reset by inputting a reset signal (see FIG. 3C).

  Next, the absolute value of the current from the first absolute value detection circuit 83a and the current gate detection level are input to the comparator 841 of the current gate generation circuit 84a via the detection circuit 77a, and the absolute value is the current gate detection level. Is exceeded, it is considered that glow discharge has occurred in the vacuum chamber 11, and a normal discharge signal is input to the current drop detection circuit 85 (see FIG. 3C). In this case, it is preferable to input a normal discharge signal after the phases of the output voltage waveform and the output current waveform substantially coincide with each other.

  Next, the absolute values from the first and second absolute value detection circuits 83a and 83b, the current gate detection level and the preset voltage pulse detection level are input to each comparator 841, and current gate generation is performed based thereon. The current gate signal and the voltage pulse signal from the circuit 84a and the voltage pulse generation circuit 84b are input to the voltage drop detection circuit 85, and the high-speed clock signal is input to the voltage drop detection circuit 85 to start detection of the occurrence of arc discharge (FIG. 3 (c)).

  Here, when arc discharge occurs between the pair of targets 41a and 41b, first, the output voltage to the pair of targets 41a and 41b drops, and then the output current increases rapidly. In this case, the current gate signal remains “1” (ON state), but only the voltage pulse signal becomes “0” (OFF state) (see FIG. 3B). That is, in detecting the occurrence of arc discharge, the voltage drop detection circuit 85 determines whether the current gate signal is “0”, and when the current gate signal is “0”, the current gate signal is turned off. Next, when the current gate signal becomes “1”, a voltage pulse drop waiting state is entered. In this case, it is determined whether the voltage pulse signal is “1”. If the voltage pulse signal is “1”, normal glow discharge is performed. Is determined to have occurred. If the voltage pulse signal becomes “0” when the current gate signal becomes “0”, the current gate signal returns to the off state.

  On the other hand, when the voltage pulse signal becomes “0” in the voltage pulse drop waiting state where the current gate signal is “1”, it is determined that a voltage drop has occurred and arc discharge has occurred (FIG. 3 ( d)). In this case, since the voltage drop can be detected with a delay of one clock or two clocks of the high-speed clock signal, the occurrence of arc discharge can be detected quickly (see FIG. 3E).

  When the arc detection means 8 detects the occurrence of arc discharge, the occurrence of arc discharge is output to the second CPU circuit 71. For example, an oscillation switch circuit is generated by the second driver circuit 73a by a control signal from the second CPU circuit 71. The operation of each switching transistor 72a, 72b, 72c, 72d of 72 is controlled, and the output to a pair of target 41a, 41b is interrupted | blocked.

  Thus, by directly detecting the occurrence of arc discharge from the length of the voltage drop time of the output voltage waveform to the pair of targets 41a and 41b, the change in the current value between the targets 41a and 41b and the output to the targets 41a and 41b are detected. Compared with what detects an arc discharge by calculating | requiring the effective value and average value of a voltage, arc discharge generation | occurrence | production can be detected rapidly and the output from AC power supply E can be interrupted | blocked. As a result, it is possible to effectively prevent the occurrence of particles and splash by reducing the energy at the time of arc discharge, and to detect the occurrence of voltage drop when the output current is flowing. Detection can be reduced.

  If it demonstrates with reference to Fig.4 (a) thru | or FIG.4 (e), 80 is the arc detection means which concerns on other embodiment. This arc detection means 80 detects the occurrence of arc discharge only from the output voltage. The voltage transformer amplifier 810 amplifies the output voltage from the detection circuit 77a, and the absolute value of the output voltage amplified by the voltage transformer amplifier 810. And an absolute value detection circuit 820 for detecting. The arc detection means 80 includes a voltage pulse generation circuit 830 provided with a comparator 830a to which an absolute value from the absolute value detection circuit 820 and a voltage pulse detection level are input, and a voltage from the voltage pulse generation circuit 830. A voltage drop detection circuit 840 to which a pulse signal is input and a pulse width detection gate generator 841 are included.

  Next, detection of occurrence of arc discharge in the arc detection circuit 80 will be described. First, the AC power source E is operated in the same manner as described above to apply an AC voltage to the pair of targets 41a and 41b. In this case, a reset signal is input to the voltage drop detection circuit 840 to reset (see FIG. 4C).

  Next, the absolute value from the absolute value detection circuit 820 and the preset voltage pulse detection level are input to the comparator 830a, the voltage pulse signal is output from the voltage pulse generation circuit 830 to the voltage drop detection circuit 840, and normal The discharge signal and the high-speed clock signal are input to the voltage drop detection circuit 840, and the detection of the occurrence of arc discharge is started (see FIG. 4C). Then, from the voltage pulse signal input to the voltage drop detection circuit 840, the pulse width detection gate generator 841 creates a voltage gate signal having a pulse width which is a normal glow discharge state, and the voltage gate signal is “1” ( When only the voltage pulse signal becomes “0” (off state) while being in the on state), the occurrence of arc discharge is detected from the drop in the output voltage (see FIG. 4B).

  That is, in the detection of the occurrence of arc discharge, when the voltage gate signal is “0” in the voltage drop detection circuit 840, the voltage gate signal is in an off state. Next, when the voltage gate signal becomes “1”, a voltage pulse signal drop waiting state is entered. In this case, it is determined whether or not the voltage pulse signal is “1”. In this state, a normal glow discharge is generated. to decide. When the voltage gate signal becomes “0”, if the voltage pulse signal also becomes “0”, the voltage gate signal is turned off.

  On the other hand, when the voltage pulse signal becomes “0” in the voltage pulse signal drop waiting state, it is determined that a voltage drop has occurred and arc discharge has occurred (see FIG. 4D). In this case, since the voltage drop can be detected with a delay of one clock or two clocks of the high-speed clock signal, the occurrence of arc discharge can be detected quickly (see FIG. 4E).

  As a result, since the occurrence of arc discharge is detected only by the voltage between the pair of targets 41a and 41b, it is not necessary to consider the phase shift between the voltage and the current, and the phase of the voltage and the current does not match, such as at the start But arc discharge can be detected.

  In the above embodiment, the voltage gate signal is directly generated through the absolute value. However, the present invention is not limited to this. For example, the relative detection voltage width is changed. May be. In this case, the non-arc discharge state is detected by another method, and the voltage width in the case of non-arc discharge is relatively determined, and the decrease in the arc voltage width is detected based on this. It may be.

  If it demonstrates with reference to Fig.5 (a) and FIG.5 (b), 9 is the arc detection means which concerns on other embodiment. This arc detection means 9 also detects the occurrence of arc discharge only from the output voltage, and a voltage transformer amplifier 91 that amplifies the output voltage from the detection circuit 77a, and a publicly known technique that enables removal of noise in the output voltage. Noise filter 92 and differentiation circuit 93. An output from the differentiation circuit 93 is input to an absolute value detection circuit 94, and a voltage pulse generation circuit 95 provided with a comparator 95a to which the absolute value and the voltage differential waveform detection level are input is provided.

  Next, detection of occurrence of arc discharge in the arc detection circuit 9 will be described. First, the AC power source E is operated in the same manner as described above to apply an AC voltage to the pair of targets 41a and 41b. Next, the absolute value from the absolute value detection circuit 94 that has passed through the differentiation circuit 93 and a preset voltage differential waveform detection level are input to the comparator 95a. In this case, when the absolute value is lower than the voltage differential waveform detection level, it is determined that normal glow discharge has occurred. On the other hand, when the absolute value exceeds the voltage differential waveform detection level, it is determined that arc discharge has occurred (see FIG. 5B).

  As a result, the arc discharge detection circuit 9 can be realized with a simple circuit configuration. In addition, since the occurrence of arc discharge is detected only by the voltage between the targets 41a and 41b, the phase shift between the voltage and the current is taken into consideration. Therefore, it is possible to detect the occurrence of arc discharge even when the phase of voltage and current does not match, such as during startup.

  If it demonstrates with reference to Fig.6 (a) and FIG.6 (b), 90 is the arc detection means which concerns on other embodiment. The arc detection means 90 detects the occurrence of arc discharge from the difference waveform between the output voltage waveform and the output current waveform, and a current sensor amplifier 910 and current transformer amplifier that amplify the output voltage and output current from the detection circuit 77a. 920, known noise filters 930a and 930b that can remove noise in the output voltage waveform and output current waveform, and adjustment so that the amplitudes of the output voltage waveform and output current waveform that have passed through the noise filters 930a and 930b are substantially the same. First and second gain adjustment circuits 940a and 940b.

The arc detection means 90 is a differential amplifier having a known structure in which the output voltage and the output current that have passed through the first and second gain adjustment circuits 940a and 940b are respectively input and differentiated according to the difference between them. 950, an absolute detection circuit 960 that detects the absolute value of the difference value from the differential amplifier 950, and a differential waveform detection circuit 970 provided with a comparator 970a to which the absolute value and the differential waveform detection level are input. And have.

  Next, detection of occurrence of arc discharge in the arc detection circuit 90 will be described. First, the AC power source E is operated in the same manner as described above to apply an AC voltage to the pair of targets 41a and 41b. Next, on / off of each switching transistor 72a, 72b, 72c, 73d of the oscillation switch circuit 72 is controlled by the second driver circuit 73a by the control signal from the second CPU circuit 71, and the output voltage and output current are controlled. Control is performed so that the phases substantially coincide with each other.

  Next, according to the output voltage and output current detected by the detection circuit 77a, the second CPU circuit 71 converts the current gain adjustment signal and the voltage gain adjustment signal into the first and second gain adjustment circuits 940a and 940b. And the first and second gain adjusting circuits 940a and 940b adjust the output voltage waveform and the output current waveform so that the amplitudes of the output voltage waveform and the output current waveform substantially coincide with each other. Enter in 950.

Next, the absolute value of the difference value passed through the absolute value detection circuit 960 from the differential amplifier 950 and a preset difference waveform detection level are input to the comparator 970a. In this case, the absolute value of the difference value is lower than the differential waveform detection level, it is determined that the normal glow discharge occurs. On the other hand, when the absolute value exceeds the differential waveform detection level, it is determined that arc discharge has occurred (see FIG. 6B).

  As a result, the waveform used for arc detection is synthesized from the difference between the appropriately adjusted current waveform and voltage waveform, so that when an arc discharge occurs, the output of the differential waveform becomes a larger output waveform. (See FIG. 6B), it is difficult to be affected by noise, and as a result, false detection can be reduced.

  In the above embodiment, a description has been given of the case where two pairs of targets 41a and 41b are arranged in the vacuum chamber 11. However, the present invention is not limited to this, and a plurality of (three or more) targets are used. The arc detection method of the present invention can also be applied to a configuration in which one AC power source is allocated in parallel so that an AC voltage is alternately applied to at least two targets.

The figure which shows typically the sputtering device of this invention. The figure explaining AC power supply. (A) is a figure which illustrates an arc detection means roughly. (B) is a figure explaining the change at the time of arc discharge generation of the signal from a current waveform and a voltage waveform. FIG. 6C is a diagram for explaining signal input to the voltage drop detection circuit. (D) is a flowchart explaining arc discharge detection. (E) is a figure which expands and shows the change of the signal at the time of the arc discharge shown to (b). (A) is a figure which illustrates schematically the arc detection means which concerns on another form. (B) is a figure explaining the change at the time of arc discharge generation of the signal from a voltage waveform. FIG. 6C is a diagram for explaining signal input to the voltage drop detection circuit. (D) is a flowchart explaining arc discharge detection. (E) is a figure which expands and shows the change of the signal at the time of the arc discharge shown to (b). (A) is a figure which illustrates schematically the arc detection means which concerns on another form. (B) is a figure explaining the change at the time of arc discharge generation of a voltage waveform. (A) is a figure which illustrates schematically the arc detection means which concerns on another form. (B) is a figure explaining the change at the time of arc discharge generation of a difference waveform.

1 Sputtering equipment
41a, 41b Target 6 Power supply unit 7 Oscillating unit 8 Arc detection means E AC power source K Power cable

Claims (18)

A voltage is alternately applied to a pair of targets provided in the vacuum chamber at a predetermined frequency via an AC power source, and each target is alternately switched between an anode electrode and a cathode electrode. A sputtering method in which a plasma atmosphere is formed by causing glow discharge to be generated and sputtering is performed on each target, the output voltage waveform to the pair of targets is detected, and when the voltage drop time of this output voltage is normal The sputtering method characterized by shutting off the output from the AC power supply when it is determined that the time is shorter than that. Detecting an output current waveform between said pair of targets mutually the absolute value of the output current exceeds a predetermined value, it is considered that the glow discharge occurs, making current gate signal from the absolute value of the output current together, it creates a voltage pulse signal from the absolute value of the output voltage, when the voltage pulse signal in the on state of the current gate signal is turned off, the voltage drop time of the output voltage than the normal glow discharge short The sputtering method according to claim 1, wherein it is determined that the time is reached.   3. The sputtering method according to claim 1, wherein the phase of the output current waveform and the output voltage waveform to the target is substantially matched during the sputtering.   The sputtering method according to claim 2, wherein the predetermined value is changed according to input power from the AC power source to the pair of targets. Together making a voltage pulse signal from the absolute value of the output voltage, and detects the pulse width of the voltage pulse signal, when the pulse width is smaller than the predetermined value, the voltage drop time of the output voltage is normal The sputtering method according to claim 1, wherein it is determined that the time is shorter than that during glow discharge. It said predetermined value, either determined directly from the absolute value of the output voltage or sputtering method of claim 5, wherein the relatively determined previously measured by the pulse width in the case of not generating the arc discharge. Detecting the differential waveform is proportional to the voltage drop of the output voltage, when the absolute value of the differential value is greater than a predetermined value, than when the voltage drop time is normal glow discharge of the output voltage waveform The sputtering method according to claim 1, wherein the sputtering method is determined to be a short time.   8. The sputtering method according to claim 7, wherein noise in the output voltage waveform is removed through a filter circuit prior to detecting the differential waveform.   The sputtering method according to claim 7 or 8, wherein the output voltage waveform is a substantially sine wave. An output current waveform between the pair of targets is detected, and after adjusting the phase and amplitude of the output voltage waveform and the output current waveform to substantially coincide with each other, a differential waveform of these waveforms is detected, and the difference value 2. The sputtering method according to claim 1, wherein when the absolute value exceeds a predetermined value, the voltage drop time of the output voltage waveform is determined to be shorter than that during normal glow discharge.   11. The sputtering method according to claim 10, wherein noise of an output voltage waveform and an output current waveform is removed through a filter circuit prior to detecting the differential waveform.   The sputtering method according to claim 10 or 11, wherein the output voltage waveform and the output current waveform are substantially sine waves. A pair of targets provided in the vacuum chamber, and an AC power supply that alternately applies a voltage at a predetermined frequency and applies a voltage between the pair of targets, and the voltage drop time of the output voltage to the target is normal A sputtering apparatus comprising: an arc detecting means for detecting a voltage drop that is shorter than that during a glow discharge; and an interrupting means for interrupting an output from an AC power source by an output from an arc detecting circuit.   14. The sputtering apparatus according to claim 13, wherein the AC power supply is provided with phase adjusting means for substantially matching the phases of the output voltage waveform and the output current waveform to the pair of targets. The arc detection means includes a first absolute value detection circuit and a second absolute value detection circuit for detecting an absolute value of an output current and an output voltage between the pair of targets, and a first absolute value detection circuit and a second absolute value. A current gate signal generation circuit and a voltage pulse signal generation circuit provided with a comparator to which an absolute value and a detection level from the detection circuit are respectively input, and a current gate signal and a voltage from the current gate signal generation circuit and the voltage pulse signal generation circuit When the voltage gate signal is turned off when the current gate signal is on, the voltage drop is detected for a shorter time than during normal glow discharge. The sputtering apparatus according to claim 13 or 14, wherein the sputtering apparatus is characterized. Said arc detecting means includes absolute value detecting circuit for detecting the absolute value of the output voltage between said pair of targets mutually voltages provided a comparator absolute value and the detection level from the absolute value detection circuit is input It consists of a pulse generation circuit and a voltage drop detection circuit to which the voltage pulse signal from the voltage pulse generation circuit is input. The pulse width of the voltage pulse signal input to the voltage drop detection circuit is detected, and this pulse width is predetermined. 15. The sputtering apparatus according to claim 13, wherein a voltage drop that is shorter than a normal glow discharge is detected when the value is smaller than the value. It said arc detecting means includes a differentiating circuit for detecting a differential waveform which is proportional to the voltage drop of the output voltage between said pair of targets mutually and absolute value detection circuit for detecting the absolute value of a differential value in the differential circuit, A voltage differential waveform circuit having a comparator to which the absolute value from the absolute value detection circuit and the detection level are input. When the absolute value of the differential value exceeds a predetermined value, normal glow discharge The sputtering apparatus according to claim 13 or 14, wherein a voltage drop that is shorter than the time is detected. The arc detection means includes first and second gain adjustment circuits that adjust the amplitudes of the output voltage waveform and the output current waveform between the pair of targets to substantially match each other, and the output voltage from each gain adjustment circuit. A differential amplifier that detects a difference waveform between the waveform and the output current waveform, an absolute value detection circuit that detects an absolute value of a difference value in the differential amplifier , a differential waveform from the absolute value detection circuit, and a detection level It is composed of a differential waveform detection circuit that has a comparator to be input, and detects a voltage drop that is shorter than normal glow discharge when the absolute value of the differential value exceeds a predetermined value. The sputtering apparatus according to claim 13 or 14, wherein:

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