JPH04253411A - Matching control system for rf generator - Google Patents

Abstract

PURPOSE:To present the matching control method of an RF generator used for a semiconductor manufacture device or the like with high efficiency and stable quality by turning reflected power to zero in a short time and maximizing power supplied to a load by most effectively controlling the impedance matching of the RF generator used for sputtering or the like. CONSTITUTION:Input power Pi and reflected power Pr detected by a power detector in an RF power source is inputted to a Kr arithmetic circuit 1 of an impedance matching box and an output Kr is obtained. The Kr is inputted to a CPU after receiving A/D conversion at an A/D converter 3. While referring to a memory 9, the CPU 8 sets the matching position and limiter set value of a variable condenser, next drives driving motor M1 and M2 through a motor control circuit 7 and obtains matching.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention distinguishes matching points and limit settings under past load conditions by process number,
The present invention relates to a variable capacitor control method in which a matching time can be brought close to zero by providing a preset function and reading these values and setting them before operation of the RF power source if necessary.

0002

[Prior Art] Conventionally, in an AC power supply circuit shown in FIG. 1 in which an RF power source, a matching box, and a load are connected in series, a power detector (PD) 4 built in the RF power source detects reflected power Pr or traveling wave power. Pi is detected and variable capacitors C1 and C2 in a matching box as shown in FIG. 2 are controlled so that the reflected power Pr becomes zero.

FIG. 3 shows an example of this, in which an output signal Kr from a Kr calculation circuit 1 is detected by an A/D converter 3, and is sent to a motor M1 via a motor control circuit 7 controlled by a CPU 8.
, M2, variable capacitors C1 and C2 directly connected to the motor are varied. Output signal K of Kr calculation circuit
The positions of the variable capacitors C1 and C2 when r becomes zero are called matching points, and it is desirable that the motor control time between them is short.

For this purpose, a position detector 2 connected to the motors M1 and M2 is provided, and its output signal VC is sent to an A/D converter 3.
The current position (address) of the variable capacitor is recognized, and the output signal VC of the position detector 2 and the limit value of the variable capacitor specified by the operation circuit 10 are input to the limiter circuit 4 via the CPU 8, and the variable capacitor is moved. When the variable capacitor position exceeds the limit value, the iNH signal from the limiter circuit 4 is output to the motor control circuit 7 to stop the motor. By setting the movable range of the variable capacitor as described above and narrowing the width, it is possible to shorten the matching time.

Conventionally, each time the load condition changes, a limiter value is set within a range in which it is estimated that a matching point cannot be detected, and the above operation is repeated to obtain matching. Therefore, it is difficult to significantly reduce the time required to find the matching point, and even if the matching point is known under the same load conditions as in the past, the variable capacitor must be manually moved to that value to start. There was a drawback.

[0006]

[Problems to be Solved by the Prior Art] The present invention presets a variable capacitor in a matching box connected in series to an RF power source by referring to past matching data before the RF power source starts operating. This is an attempt to shorten the matching time during RF power supply operation.

[0007]

[Means of the present invention for solving the problems]

[Example] Data storage method of matching points under different load conditions and operating circuit 1 in the circuit shown in FIG.
Examples of 0 are shown in FIGS. 4 and 5, respectively. Figure 4 is an example of a data table on battery-backed RAM or non-volatile RAM.
) to distinguish by incrementing the N of that PRCS.
Corresponding to O, a table is prepared in which a pair of address data indicating a matching point of variable capacitors C1 and C2 and a limit setting value at that time is set. The initial values of these values are, for example, the limiter value set to the maximum and minimum of the variable range of the variable capacitor, and the matching position set to the center value.

The operation key LIMIT shown in FIG. 5 is a mode key for setting limit values, and is
Display limit setting values by operating the P and DOWN keys. The PRST key can be used to register the above-mentioned limit setting value in the memory, and when a matching point is detected during RF power supply operation, this key can be used to register it in the address memory of the variable capacitors C1 and C2 at that time.

[0009] The READ key is pressed when the RF power is stopped.
By calling the matching address for C1 and C2 of PRCS NO at that time using this key, PR
It is possible to recognize the relationship between the load condition corresponding to the CS NO and the matching point. The AUT/MAN key is a key to switch between automatic and manual operation, and when operating manually, UP,
With the DOWN key, C1 and C2 can be directly varied manually.

[0010] Figures 6 and 7 show examples of operation by the above key operations, and in Figure 6, the limiter value is set in PRCS NO3, and C1 and C2 are set in PRCS NO3 when the RF radio wave operation starts. The output signal Kr of the Kr arithmetic circuit decreases under the control of the circuit, a matching point is detected after the TM time, and then the operation is shown until it is registered in the memory by pressing the PRST key. Through such operations, a plurality of matching operations with different load conditions are registered in the table, distinguished by PRCSNO, using the NEXT key.

FIG. 7 shows that the data in the table shown in FIG. 4 for the load to be implemented is referred to using the READ key, and C1 and C2 are set in advance using the PRST key before the RF power supply starts operating. By presetting the matching point, in the case of the same process as in the past, it is possible to detect the matching point immediately after the RF power supply is turned on, as shown by Kr in FIG. 7, and it can be seen that this is the minimum time.

0012

[Effects of the Invention] By using the control method according to the present invention, it is possible to finish the movement of the variable capacitor while the conditions on the load side are being set for the same load or similar load as in the past process, so that matching can be achieved. It is clear that the time can be saved significantly. As a result, not only is there an economic effect such as improved productivity in equipment operating time and reduced power consumption during the time required to obtain matching points, but also a production process with less power fluctuations until matching is achieved, resulting in more stable quality. It can also be measured.

[Brief explanation of the drawing]

[Figure 1] Main circuit configuration diagram of RF generator

[Figure 2] Matching box internal circuit diagram

[Figure 3] Matching control circuit configuration diagram

FIG. 4 is a block diagram of a data storage method of the operation circuit in the matching control circuit of the present invention.

FIG. 5 is a block diagram of the operating section of the operating circuit in the matching control circuit of the present invention.

[Figure 6] Matching control operation waveform of the present invention

[Figure 7] Matching control operation waveform of the present invention

[Explanation of symbols]

1A RF power supply 2A Matching box 3A Load 4A Power detector (PD) L Matching box inductance C
1 Matching box variable capacitor C2 Matching box variable capacitor 1 Kr calculation circuit 2 Position detector 3 A/D converter 4 Limiter circuit 5 Motor M1 6 Motor M2 7 Motor control circuit 8 CPU 9 Memory 10 Operation circuit

Claims (1)

[Claims] 1. In an AC power supply circuit in which an RF power source, a matching box, and a load are connected in series, two variable capacitors built in the matching box and connected in series and parallel to the power supply circuit are directly connected to a motor, and the RF A power detector inside the power supply measures the reflected power against the traveling wave power as A.
A /D converter is provided to detect the reflected power, and a motor control circuit and an operation circuit are provided to control the reflected power to zero, and a signal is provided to prohibit the movement of the variable capacitor at the set value of the matching position and the limiter setting position. In a matching control circuit that has a limiter circuit, etc. that outputs the value to the motor control circuit, when the RF power supply indicates the matching point during operation, the current position data of the variable capacitor is set to the limiter by a signal from the operating circuit or external interface circuit. battery-backed RAM or non-volatile RAM with values
The operation of storing data in the above table is performed for each case with different load conditions, and when the RF power supply stops, the current variable capacitor position is referred to from the above table according to the load conditions to be operated next time, and the matching point is set. A matching control method characterized by moving in advance, presetting a limiter setting value in a limiter circuit, and starting a matching operation.