CN116949412A - A kind of plasma radio frequency power supply arc detection and its suppression method - Google Patents

Abstract

The invention discloses a plasma radio frequency power arc detection and suppression method, which comprises the steps of firstly obtaining output voltage and output current of a radio frequency power supply through a sampling circuit module, distinguishing micro arcs and hard arcs through specific discriminant criteria, adopting corresponding control strategies to perform arc suppression treatment, finally realizing rapid detection and effective suppression of the arcs, improving film deposition quality, avoiding irreversible damage on the surface of a workpiece, finally designing optimal micro arc parameters of the plasma radio frequency power supply, and calculating optimal micro arc interruption time and related parameters by adjusting micro arc interruption time, voltage threshold and current threshold, recording the frequency of the hard arcs and the soft arcs, so as to realize optimal treatment of the micro arcs. By using the plasma radio frequency power supply arc detection and suppression technology provided by the invention, the generation of the arc can be detected and suppressed in time, the surface of a workpiece is protected, the film deposition quality is improved, and the reject ratio of the workpiece is reduced.

Description

A kind of plasma radio frequency power supply arc detection and its suppression method

Technical field

The invention relates to the field of plasma thin film deposition processes, and specifically relates to a radio frequency power supply arc detection and suppression method used in the plasma thin film deposition process.

Background technique

Plasma processing equipment is widely used in the field of semiconductor processing, such as physical vapor deposition (PVD) and chemical vapor deposition (CVD). For example, the common plasma-enhanced chemical vapor deposition PECVD uses plasma generated by glow discharge to decompose gases and react quickly to form thin films.

RF power supplies are widely used in plasma thin film deposition processes such as PECVD and PVD. In the thin film deposition process, radio frequency power is used to excite and generate plasma. Due to factors such as local charge accumulation on the surface of the workpiece, surface tip discharge, changes in the cavity atmosphere, etc., arc ignition is prone to occur. If effective measures are not taken in time, it will affect the quality of film deposition and even cause irreversible damage to the surface of the workpiece, leading to scrapping of the workpiece. . Therefore, in the plasma thin film deposition process, rapid arc detection and effective arc suppression are crucial. In order to reduce the adverse effects of arc discharge, it is hoped that the arc can be automatically detected in the early stages of the arc formation process, so that the power output can be turned off as early as possible and the harm of the arc that has occurred can be reduced. By proposing a new plasma RF power arc detection and suppression technology, the stability and yield of the thin film deposition process can be effectively improved.

Contents of the invention

In order to solve the above problems, the present invention proposes a plasma radio frequency power supply arc detection and suppression method, which includes a radio frequency power supply output voltage sensing and sampling circuit module, a radio frequency power supply output current sensing, sampling circuit module and an arc detection and suppression module. Obtain the output voltage and output current of the RF power supply through the voltage sensor and current sensor; compare the output voltage and output current with the preset voltage threshold and current threshold to identify micro arcs and hard arcs; control the RF power supply based on the detection results The output is interrupted and the arc is extinguished to avoid damage to the workpiece; after the hard arc interruption time, the output of the RF power supply is gradually restored to ensure the continuity and stability of the work.

In order to achieve the above objects, the technical solutions adopted by the present invention are:

A plasma radio frequency power supply arc detection and suppression method, which is characterized in that it includes the following steps:

S1: Arc detection of plasma RF power supply through arc detection module:

S11: Use the output voltage sampling module to obtain the output voltage Uo of the radio frequency power supply;

S12: Use the output current sampling module to obtain the output current Io of the radio frequency power supply;

S13: Compare the output voltage Uo with the preset voltage threshold Uth, and compare the output current Io with the preset current threshold Ith. When Uo is less than Uth and Io is greater than Ith, it is determined to be a UXI arc, that is, a micro arc. , compare the output current Io with the preset current threshold Ith1. When Io is greater than Ith1, it is determined to be an Imax arc, that is, a hard arc;

S2: Suppress the plasma RF power arc through the arc suppression module:

S21: When it is determined that a micro-arc occurs, the output of the radio frequency power supply is controlled to be turned off according to the predetermined micro-arc interruption time Tmicro, so that the micro-arc is extinguished;

S22: When it is determined that a hard arc occurs, the output of the RF power supply is controlled to turn off according to the predetermined hard arc interruption time TImax, so that the hard arc is extinguished; after the TImax time, the RF power supply output is controlled to restart the ramp according to the predetermined slope and resume output;

S3: Design the optimal micro-arc parameters of plasma RF power supply:

S31: Set the voltage threshold Uth related to micro-arc to the minimum value, and set the current threshold Ith to the maximum value;

S32: Enable the hard arc action function and turn off the soft arc action function;

S33: Record the frequency of hard arc and soft arc occurrence of the radio frequency power supply at this time, that is, the number of hard arc and soft arc occurrence per unit time, recorded as RImax0 and RUXI0 respectively;

S34: Enable hard arc and soft arc action functions at the same time, and set the micro-arc interruption time Tmicro to the minimum value;

S35: Record the frequency of hard arc and soft arc occurrence of the radio frequency power supply at this time, that is, the number of hard arc and soft arc occurrence per unit time, recorded as RImax1 and RUXI1 respectively;

S36: Increase the micro-arc interruption time gradually, and record the frequency of hard arc and soft arc occurrence of the radio frequency power supply at each time TmicroI (I=1, 2, 3,...), that is, the frequency of hard arc and soft arc occurrence per unit time. The times are recorded as RImaxI and RUXII (I=1, 2, 3,...) respectively;

S37: Gradually increase the voltage threshold Uth, decrease the current threshold Ith, and repeat steps S2 to S6;

S38: Calculate the occurrence ratio of hard arc and soft arc in each case. The calculation formula is: R1Imax= RImax0/RImaxI, R1UXI= RUXI0/RUXII;

S39: Calculate the micro-arc interruption time of the radio frequency power supply in each case. The calculation formula is: TI=TmicroI*R1UXI;

S310: Evaluate the optimal settings of the micro-arc, and obtain the optimal micro-arc parameters based on the optimal position. The optimal micro-arc parameters are such that the hard arc occurrence rate is maximized and the micro-arc interruption time is the shortest.

In the above structure: the invention proposes a plasma radio frequency power supply arc detection and suppression method, which includes the following steps: first, arc detection is performed on the plasma radio frequency power supply through an arc detection module, and then the plasma radio frequency power supply is detected through an arc suppression module. The arc of the RF power supply is suppressed, and finally, the optimal micro-arc parameters of the plasma RF power supply are designed.

Among them, when the arc detection module is used to detect the arc of the plasma radio frequency power supply, the output current and output voltage of the radio frequency power supply are obtained respectively through the installed output voltage sampling module and the output current sampling module, and then the set arc detection module is used to perform the detection. The output voltage and output current are compared with the preset voltage threshold and current threshold, micro arc and hard arc are identified, and arc detection of the RF power supply output is completed.

When the arc detection module performs arc detection, it obtains the output voltage and output current of the radio frequency power supply through the voltage sensor and current sensor respectively, and compares them with the preset voltage threshold and current threshold to identify micro arcs and hard arcs. Arc detection through the arc detection module can promptly detect and identify arc problems, providing an accurate basis for subsequent arc suppression processing.

When an arc occurs, the arc suppression module needs to be used to suppress the arc of the plasma RF power supply. The output voltage of the RF power supply changes faster than the current change. You can quickly determine whether the arcing phenomenon has occurred by detecting the output voltage amplitude of the RF power supply. And quickly turn off the RF power supply output pulse voltage. At this time, the arc current is only slightly higher than the steady-state output current. The arc type is micro arc. If the output voltage is lower than the set voltage threshold uth and the output current is greater than the set current threshold ith determines the arc as a micro arc. If the output current increases too quickly when an arc occurs and is greater than the preset current threshold ith1, the arc will be determined as a hard arc.

When the arc suppression module performs arc suppression, it controls the output of the radio frequency power supply to interrupt and extinguish the arc according to the detected arc type. For example, when a micro-arc is detected, the output of the radio frequency power supply is controlled to be turned off according to a predetermined micro-arc interruption time to prevent the micro-arc from further developing into a hard arc. When a hard arc is detected, the output of the RF power supply is controlled to be turned off for a period of time according to the predetermined hard arc interruption time to extinguish the hard arc.

Finally, the optimal micro-arc parameters of the plasma RF power supply are designed. By recording the frequency of hard arc and soft arc occurrences, and gradually adjusting the micro-arc interruption time, voltage threshold, and current threshold, the optimal micro-arc parameters are calculated. In this way, the rate of hard arc occurrence can be minimized, the micro-arc interruption time can be minimized, and the optimal micro-arc suppression effect can be achieved, thereby designing the optimal micro-arc parameters of the plasma RF power supply.

As a preferred technical solution of the present invention: it also includes a full-bridge inverter, the output voltage sampling module and the output current sampling module are respectively connected to an arc detection module, the arc detection module is connected to an arc suppression module, and the arc suppression module is connected to a full-bridge inverter. Bridge inverter, the full-bridge inverter is connected to the load. When a hard arc is determined to occur, the output of the RF power supply is controlled to be turned off according to the predetermined hard arc interruption time TImax. After the TImax time, the RF power supply output passes through the full bridge The inverter outputs to the load to achieve continuity of output current.

In the above structure: the continuity of the output current can be achieved by setting up a full-bridge inverter. When a hard arc is determined to occur, the output of the RF power supply is controlled to be turned off according to the predetermined hard arc interruption time TImax. After the TImax time, the RF power supply The output is output to the load through the full-bridge inverter, therefore, the continuity of the output current is achieved.

As a preferred technical solution of the present invention: the output voltage sampling module includes a voltage sensor and a voltage sampling circuit, the voltage sensor is connected to the output end of the voltage sampling circuit and the radio frequency power supply respectively, and the output current sampling module includes a current sensor and a current Sampling circuit, the current sensor is connected to the output end of the current sampling circuit and the radio frequency power supply respectively.

As a preferred technical solution of the present invention: the voltage sampling circuit and the current sampling circuit are respectively connected to the arc detection module and used to input the obtained output voltage Uo and output current Io of the radio frequency power supply.

In the above structure: the output voltage sampling module includes a voltage sensor and a voltage sampling circuit. The voltage sensor is connected to the voltage sampling circuit and the output end of the radio frequency power supply respectively, and the output voltage of the radio frequency power supply is collected through the voltage sensor. The output current sampling module includes a current sensor and a current The sampling circuit and the current sensor are respectively connected to the output terminals of the current sampling circuit and the radio frequency power supply. The output current of the radio frequency power supply is collected through the current sensor. The voltage sampling circuit and the current sampling circuit are respectively connected to the arc detection module. The input voltage sensor and current sensor Obtain the output voltage Uo and output current Io of the RF power supply to the arc detection module.

Compared with the prior art, the beneficial effects of the present invention are:

(1) The sampling module of RF power supply output voltage and current can monitor the occurrence and changes of arc in real time to ensure rapid detection of arc.

(2) Distinguish micro arcs and hard arcs through discrimination criteria, and adopt corresponding control strategies to suppress arcs, which can not only prevent micro arcs from further developing into hard arcs, but also avoid damage to the workpiece surface caused by hard arcs.

(3) By gradually adjusting the micro-arc interruption time, voltage threshold, and current threshold, the optimal micro-arc parameters can be calculated. Finally, the optimal micro-arc parameters of the plasma RF power supply can be designed, and the optimal micro-arc parameters can be evaluated based on the actual process conditions. Optimize the settings to improve the surface quality of the workpiece and the film deposition effect.

Description of the drawings

Figure 1 is a principle framework diagram of the present invention;

Figure 2 is a flow chart for rapid classification detection of plasma radio frequency power arc arc in the present invention;

Figure 3 is a flow chart of arc suppression of plasma radio frequency power supply in the present invention;

Figure 4 is a schematic diagram of micro-arc determination in the present invention;

Figure 5 is a schematic diagram of hard arc determination in the present invention.

Implementation

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments:

The invention proposes a plasma radio frequency power supply arc detection and suppression method, which includes the following steps:

S1: Arc detection of plasma RF power supply through arc detection module:

S11: Use the output voltage sampling module to obtain the output voltage Uo of the radio frequency power supply;

S12: Use the output current sampling module to obtain the output current Io of the radio frequency power supply;

S13: Compare the output voltage Uo with the preset voltage threshold Uth, and compare the output current Io with the preset current threshold Ith. When Uo is less than Uth and Io is greater than Ith, it is determined to be a UXI arc, that is, a micro arc. , compare the output current Io with the preset current threshold Ith1. When Io is greater than Ith1, it is determined to be an Imax arc, that is, a hard arc;

S2: Suppress the plasma RF power arc through the arc suppression module:

S21: When it is determined that a micro-arc occurs, the output of the radio frequency power supply is controlled to be turned off according to the predetermined micro-arc interruption time Tmicro, so that the micro-arc is extinguished;

S22: When it is determined that a hard arc occurs, the output of the RF power supply is controlled to turn off according to the predetermined hard arc interruption time TImax, so that the hard arc is extinguished; after the TImax time, the RF power supply output is controlled to restart the ramp according to the predetermined slope and resume output;

S3: Design the optimal micro-arc parameters of plasma RF power supply:

S31: Set the voltage threshold Uth related to micro-arc to the minimum value, and set the current threshold Ith to the maximum value;

S32: Enable the hard arc action function and turn off the soft arc action function;

S33: Record the frequency of hard arc and soft arc occurrence of the radio frequency power supply at this time, that is, the number of hard arc and soft arc occurrence per unit time, recorded as RImax0 and RUXI0 respectively;

S34: Enable hard arc and soft arc action functions at the same time, and set the micro-arc interruption time Tmicro to the minimum value;

S35: Record the frequency of hard arc and soft arc occurrence of the radio frequency power supply at this time, that is, the number of hard arc and soft arc occurrence per unit time, recorded as RImax1 and RUXI1 respectively;

S36: Increase the micro-arc interruption time gradually, and record the frequency of hard arc and soft arc occurrence of the radio frequency power supply at each time TmicroI (I=1, 2, 3,...), that is, the frequency of hard arc and soft arc occurrence per unit time. The times are recorded as RImaxI and RUXII (I=1, 2, 3,...) respectively;

S37: Gradually increase the voltage threshold Uth, decrease the current threshold Ith, and repeat steps S2 to S6;

S38: Calculate the occurrence ratio of hard arc and soft arc in each case. The calculation formula is: R1Imax= RImax0/RImaxI, R1UXI= RUXI0/RUXII;

S39: Calculate the micro-arc interruption time of the radio frequency power supply in each case. The calculation formula is: TI=TmicroI*R1UXI;

S310: Evaluate the optimal settings of the micro-arc, and obtain the optimal micro-arc parameters based on the optimal position. The optimal micro-arc parameters are such that the hard arc occurrence rate is maximized and the micro-arc interruption time is the shortest.

The invention proposes a plasma radio frequency power supply arc detection and suppression method, which includes the following steps: first, the arc detection module is used to detect the plasma radio frequency power supply arc, and then the arc suppression module is used to detect the plasma radio frequency power supply arc. suppress, and finally, design the optimal micro-arc parameters of the plasma RF power supply.

As shown in Figure 2, when the arc detection module is used to detect the arc of the plasma RF power supply, the output current and output voltage of the RF power supply are obtained respectively by setting and installing the output voltage sampling module and the output current sampling module. The arc detection module compares the output voltage and output current with the preset voltage threshold and current threshold, identifies micro arc and hard arc, and completes the arc detection of the RF power supply output.

When the arc detection module performs arc detection, it obtains the output voltage and output current of the radio frequency power supply through the voltage sensor and current sensor respectively, and compares them with the preset voltage threshold and current threshold to identify micro arcs and hard arcs. Arc detection through the arc detection module can promptly detect and identify arc problems, providing an accurate basis for subsequent arc suppression processing.

When an arc occurs, the arc suppression module needs to be used to suppress the arc of the plasma RF power supply. The output voltage of the RF power supply changes faster than the current change. You can quickly determine whether the arcing phenomenon has occurred by detecting the output voltage amplitude of the RF power supply. And quickly turn off the RF power supply output pulse voltage. At this time, the arc current is only slightly higher than the steady-state output current. The arc type is micro-arc. The identification of micro-arc is explained in conjunction with Figure 4. If the output voltage is lower than the set voltage If the threshold uth and the output current is greater than the set current threshold ith, the arc will be determined as a micro arc. The identification of hard arc is explained with reference to Figure 5. If the output current increases too fast when the arc is generated and is greater than the preset current threshold ith1, the arc will be judged as a hard arc.

In Figure 4: uth is the preset voltage threshold, ith is the preset current threshold, and Tmicro is the preset micro-arc turn-off time.

In Figure 5: ith1 is the preset hard arc current threshold, and TImax is the preset hard arc cut-off time.

As shown in Figure 3, when the arc suppression module performs arc suppression, it controls the output of the radio frequency power supply to interrupt and extinguish the arc according to the detected arc type. For example, when a micro-arc is detected, the output of the radio frequency power supply is controlled to be turned off according to a predetermined micro-arc interruption time to prevent the micro-arc from further developing into a hard arc. When a hard arc is detected, the output of the RF power supply is controlled to be turned off for a period of time according to the predetermined hard arc interruption time to extinguish the hard arc.

Finally, the optimal micro-arc parameters of the plasma RF power supply are designed. By recording the frequency of hard arc and soft arc occurrences, and gradually adjusting the micro-arc interruption time, voltage threshold, and current threshold, the optimal micro-arc parameters are calculated. In this way, the rate of hard arc occurrence can be minimized, the micro-arc interruption time can be minimized, and the optimal micro-arc suppression effect can be achieved, thereby designing the optimal micro-arc parameters of the plasma RF power supply.

As shown in Figure 1, this implementation also includes a full-bridge inverter. The output voltage sampling module and the output current sampling module are respectively connected to an arc detection module. The arc detection module is connected to an arc suppression module. The arc suppression module The module is connected to a full-bridge inverter, and the full-bridge inverter is connected to the load. When a hard arc is determined to occur, the output of the RF power supply is controlled to be turned off according to the predetermined hard arc interruption time TImax. After the TImax time, the RF power supply output It is output to the load through the full-bridge inverter to achieve continuity of the output current.

Through the set full-bridge inverter, the continuity of the output current can be achieved. When a hard arc is determined to occur, the output of the RF power supply is controlled to be turned off according to the predetermined hard arc interruption time TImax. After the TImax time, the RF power supply output passes through the full bridge The inverter outputs to the load, therefore, achieving continuity of the output current.

In this embodiment: the output voltage sampling module includes a voltage sensor and a voltage sampling circuit. The voltage sensor is connected to the voltage sampling circuit and the output end of the radio frequency power supply respectively. The output current sampling module includes a current sensor and a current sampling circuit. , the current sensor is connected to the output end of the current sampling circuit and the radio frequency power supply respectively. The voltage sampling circuit and the current sampling circuit are respectively connected to the arc detection module and used to input the obtained output voltage Uo and output current Io of the radio frequency power supply.

The output voltage sampling module includes a voltage sensor and a voltage sampling circuit. The voltage sensor is connected to the output end of the voltage sampling circuit and the radio frequency power supply respectively. The output voltage of the radio frequency power supply is collected through the voltage sensor. The output current sampling module includes a current sensor and a current sampling circuit. The current The sensors are connected to the output terminals of the current sampling circuit and the radio frequency power supply respectively. The output current of the radio frequency power supply is collected through the current sensor. The voltage sampling circuit and the current sampling circuit are respectively connected to the arc detection module. The input voltage sensor and the current sensor obtain the output current of the radio frequency power supply. Output voltage Uo and output current Io to the arc detection module.

In summary:

The invention adopts a sampling module for the output voltage and current of the radio frequency power supply, which can monitor the occurrence and change of the arc in real time and ensure the rapid detection of the arc.

The present invention distinguishes micro-arcs and hard arcs through discrimination criteria, and adopts corresponding control strategies to perform arc suppression processing, which can not only prevent micro-arcs from further developing into hard arcs, but also avoid damage to the workpiece surface caused by hard arcs.

The present invention calculates the optimal micro-arc parameters by gradually adjusting the micro-arc interruption time, voltage threshold, and current threshold. Finally, the optimal micro-arc parameters of the plasma radio frequency power supply can be designed, and the optimal micro-arc can be evaluated according to the actual process conditions. settings to improve the surface quality of the workpiece and the film deposition effect.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any modifications or equivalent changes based on the technical essence of the present invention still fall within the scope of protection claimed by the present invention. .

Claims (4)

1. A plasma radio frequency power supply arc detection and suppression method is characterized in that: the method comprises the following steps:

s1: arc detection is carried out on the plasma radio frequency power supply through an arc detection module:

s11: obtaining the output voltage Uo of the radio frequency power supply by using an output voltage sampling module;

s12: obtaining output current Io of a radio frequency power supply by using an output current sampling module;

s13: comparing the output voltage Uo with a preset voltage threshold Uth, and simultaneously comparing the output current Io with a preset current threshold Ith, when Uo is smaller than Uth and Io is larger than Ith, judging as UXI arcs, namely micro arcs, and comparing the output current Io with a preset current threshold Ith1, and when Io is larger than Ith1, judging as Imax arcs, namely hard arcs;

s2: suppressing the plasma radio frequency power supply arc through an arc suppression module:

s21: when the occurrence of the micro-arc is judged, the output of the radio frequency power supply is controlled to be turned off according to the preset micro-arc interruption time Tmicro, so that the micro-arc is extinguished;

s22: when judging that the hard arc occurs, controlling the output of the radio frequency power supply to be turned off according to the preset hard arc interruption time TImax, so that the hard arc is extinguished; after the TImax time, controlling the output of the radio frequency power supply to restart climbing according to a preset slope, and recovering the output;

s3: designing optimal micro-arc parameters of a plasma radio frequency power supply:

s31: setting a voltage threshold Uth associated with the micro-arc to a minimum value and setting a current threshold Ith to a maximum value;

s32: enabling a hard arc action function and closing a soft arc action function;

s33: recording the occurrence frequency of hard arcs and soft arcs of the radio frequency power supply at the moment, namely the occurrence frequency of the hard arcs and the soft arcs in unit time, and respectively recording the occurrence frequency as RImax0 and RUXI0;

s34: enabling the hard arc action function and the soft arc action function simultaneously, and setting the micro-arc interruption time Tmicro to a minimum value;

s35: recording the occurrence frequency of hard arcs and soft arcs of the radio frequency power supply at the moment, namely the occurrence frequency of the hard arcs and the soft arcs in unit time, and respectively recording the occurrence frequency as RImax1 and RUXI1;

s36: successively increasing the micro-arc interruption time, and recording the occurrence frequency of the hard arc and the soft arc of the radio frequency power supply at the moment under each Tm micro I (I=1, 2,3, …), namely the occurrence frequency of the hard arc and the soft arc in unit time, which are respectively recorded as rimaxI and RUXII (I=1, 2,3, …);

s37: successively increasing the voltage threshold Uth, decreasing the current threshold Ith, and repeating steps S2 to S6;

s38: the hard arc and soft arc occurrence ratio in each case was calculated as: r1 imax=rimax 0/RImaxI, R1UXI =ruxi 0/RUXII;

s39: the micro-arc interruption time of the radio frequency power supply under each condition is calculated, and the calculation formula is as follows: ti=tmicoi R1UXI;

s310: and (3) evaluating the optimal setting of the micro-arcs, and obtaining optimal micro-arc parameters according to the optimal positions, wherein the optimal micro-arc parameters are the most hard arc occurrence rate and the shortest micro-arc interruption time.

2. The method for detecting and suppressing an arc of a plasma radio frequency power supply according to claim 1, wherein: the full-bridge inverter is connected to the load, when the hard arc is judged to occur, the output of the radio frequency power supply is controlled to be turned off according to the preset hard arc interruption time TImax, and after the TImax time, the output of the radio frequency power supply is output to the load through the full-bridge inverter, so that the continuity of output current is realized.

3. The method for detecting and suppressing an arc of a plasma radio frequency power supply according to claim 2, wherein: the output voltage sampling module comprises a voltage sensor and a voltage sampling circuit, the voltage sensor is respectively connected with the output ends of the voltage sampling circuit and the radio frequency power supply, the output current sampling module comprises a current sensor and a current sampling circuit, and the current sensor is respectively connected with the output ends of the current sampling circuit and the radio frequency power supply.

4. A method for detecting and suppressing an arc of a plasma rf power supply according to claim 3, wherein: the voltage sampling circuit and the current sampling circuit are respectively connected to the arc detection module and are used for inputting and obtaining the output voltage Uo and the output current Io of the radio frequency power supply.