KR20050007624A - Apparatus for generating inductively coupled plasma having high plasma uniformity, and method of controlling plasma uniformity thereof - Google Patents

Abstract

PURPOSE: An inductively coupled plasma generating apparatus with high plasma uniformity is provided to make the inside of a chamber maintain optimum plasma uniformity by previously storing a value when a plurality of source gases capable of being used in etching a substrate have optimum plasma uniformity in a chamber and by using the previously stored value in performing an etch process on a real substrate. CONSTITUTION: A chamber(200) has an electrostatic chuck in which a substrate is installed. Power is applied by a high frequency power supply. A gas injection part injects source gas to the inside of the chamber. A plurality of antennas(220) receive the power from the high frequency power supply, interconnected in parallel with each other and located on the gas injection part. A plurality of sensors(230) are connected to the plurality of antennas, respectively. A variable capacitor is connected between one of the plurality of antennas and its corresponding sensor. A controller(240) receives and stores a measurement valve from the plurality of sensors and controls the variable capacitor, connected to the plurality of sensors and the variable capacitor.

Description

Apparatus for generating inductively coupled plasma having high plasma uniformity, and method of controlling plasma uniformity

The present invention relates to an inductively coupled plasma generating apparatus, and more particularly, to an inductively coupled plasma generating apparatus capable of optimally controlling the uniformity of plasma generated in a chamber and a method of controlling the plasma uniformity using the same.

With the recent development of the semiconductor-related industry, semiconductor manufacturing apparatuses are pursuing high capacity and high functionalization. Accordingly, more devices need to be integrated in a limited area. It is being researched and developed for integration.

In the semiconductor device manufacturing process for realizing the ultra-miniaturized and highly integrated semiconductor device, the reaction gas is activated and transformed into a plasma state, whereby cations or radicals of the reaction gas in the plasma state etch predetermined regions of the semiconductor substrate. Dry etching technology using plasma is widely used, and FIG. 1 shows a schematic configuration of a plasma generator using a conventional inductively coupled plasma (ICP).

The conventional inductively coupled plasma generator has a predetermined volume and includes a chamber 100 including an exhaust hole, and a gas injector 110 positioned above the chamber 100 and introducing a source gas into the chamber 100. And an antenna 120 to which the source power is applied, and an electrostatic chuck 150 to which the substrate W is fixed and to which the bias power is applied.

In addition, a load impedance of a source RF generator 140 for applying a source power to the antenna 120 and a characteristic impedance of a connection cable connected to the source RF generator 140. Source impedance matching box 130 is connected.

The antenna 120 is for receiving a high frequency power, and an example of a related art antenna related apparatus is disclosed in FIG. 2A, and FIG. 2B is an equivalent circuit diagram of FIG. 2A.

According to FIG. 2A, the antenna 120 includes a first antenna 122 and a second antenna 126 connected in parallel with the first antenna 122. The first antenna 122 is grounded at one end thereof. The other end thereof is connected to the variable load capacitors CL and 123 and the source impedance matching circuit 130, respectively, and the second antenna 126 is positioned outside the first antenna 122, one end of which is grounded. The other end thereof is connected to the variable resonant capacitor CR 127. The first antenna 122 and the second antenna 126 are mostly composed of concentric circles on the same plane, but may be arranged differently in some cases.

Reference numerals 124 and 128 of FIG. 2B denote respective impedances including both the equivalent resistance and the equivalent impedance of the first and second antennas 122 and 126.

Meanwhile, a bias high frequency oscillator 170 for applying a high frequency bias power to the electrostatic chuck 150 and a bias for matching the load impedance to characteristic impedances of a connection cable connected to the bias high frequency oscillator 170. Bias impedance matching boxes 160 are respectively connected.

The operation configuration of the conventional inductively coupled plasma generator is as follows.

First, when the substrate W is placed on the electrostatic chuck 150 and power is applied to the electrostatic chuck 150 by a power supply unit, the substrate is mounted and fixed to the electrostatic chuck 150 by electrostatic power. When the substrate is fixed to the 150, the source gas is injected from the gas injector 110 in the upper part of the chamber 100 into the chamber 100, and at the same time, the bias power is supplied to the electrostatic chuck 150, and the antenna 120 is applied to the substrate 120. When a source power source is applied to each other, a plasma P having a strong oxidizing power is formed in the chamber 100, and a process of etching a substrate is performed by the cations in the plasma generated incident and colliding with the surface of the substrate. Here, the source gas refers to a process gas mixed at an appropriate ratio for etching the substrate.

On the other hand, in the inductively coupled plasma device having the above configuration, the size of the variable load capacitor 123 for controlling the transfer energy to the second antenna 126 is determined, and the first antenna 122 and the second antenna ( 126) The size of the variable resonant capacitor 127 is determined to form a mutual resonance state, and then energy supplied from the high frequency power source is efficiently transferred to the plasma generated inside the chamber 100 to increase or decrease the uniformity of the plasma. As a result, the plasma inside the chamber 100 may be etched to the substrate in an optimal state.

However, in the plasma uniformity control method using the conventional inductively coupled plasma generator, each source gas is generated by converting each source gas as the ionization rate, ionization rate, and dissociation ratio are different for each source gas injected according to each process. Although the plasma uniformity control method is required to be different, there is a disadvantage in that it is not possible to implement the optimum plasma uniformity required for each process because it cannot but be controlled by the same operation configuration.

Moreover, such an operation configuration is particularly problematic for realizing fine patterns and high integration for substrates that are being enlarged in recent years.

The present invention has been devised to solve the above problems, in each of the different processes in the etching process for the substrate, automatically or semi-automatically to maintain the plasma uniformity of the respective source gases generated in the chamber in an optimal state It is an object of the present invention to provide a plasma generating apparatus which can be controlled and a plasma uniformity control method using the same.

1 is a schematic configuration diagram of a conventional inductively coupled plasma generator.

Figure 2a is a configuration diagram of the antenna related device of the conventional inductively coupled plasma generator.

2B is an equivalent circuit diagram of FIG. 2A.

3 is a block diagram of an inductively coupled plasma generator according to the present invention;

Figure 4 is a configuration diagram of the antenna related device of the inductively coupled plasma generating apparatus according to the present invention.

5 is a diagram illustrating a method of controlling plasma uniformity using an inductively coupled plasma generator according to the present invention.

Explanation of symbols on the main parts of the drawings

200: chamber 210: gas injection unit

220: antenna 222: first antenna

226: second antenna 223: variable load capacitor

227 variable resonance capacitor 230 sensor

232: first sensor unit 234: second sensor unit

240: controller 250: neural network controller

260: in-situ plasma diagnostic system 270: source impedance matching circuit

280: source high frequency oscillator

The present invention provides a chamber comprising an electrostatic chuck on which a substrate is placed to achieve the above object; A high frequency power supply for applying power; A gas injector for injecting a source gas into the chamber; A plurality of antennas receiving power from the high frequency power source and connected in parallel to each other and positioned on an upper end of the gas injection unit; A plurality of sensors each connected to the antenna; A variable capacitor connected between one of the antennas and a corresponding sensor; It is connected to the plurality of sensors and the variable capacitor, provides an inductively coupled plasma generator comprising a controller for receiving and storing the measured values from the plurality of sensors, and controls the variable capacitor.

More specifically, the present invention provides an inductively coupled plasma generator further comprising a neural network controller connected to the controller, and provides an inductively coupled plasma generator further comprising an in-situ plasma diagnostic system connected to the controller. The variable capacitor provides an inductively coupled plasma generator connected between an outermost antenna and a sensor corresponding thereto.

In another aspect, the present invention is the first step of injecting any source gas into the chamber through the gas injection unit using the above apparatus; Applying a high frequency source power to an antenna to discharge the source gas into plasma; Adjusting a variable capacitor connected to an antenna to optimally adjust the uniformity of the plasma; A fourth step of measuring a current and voltage value of the antenna through a sensor, inputting and storing the controller when the plasma uniformity is optimal; When the same source gas as the source gas is injected into the chamber again, the controller provides a method for controlling the uniformity of the plasma comprising a fifth step of adjusting the variable capacitor connected to the antenna based on the information stored therein.

More specifically, before the fifth step, the method of controlling the uniformity of the plasma further comprising the step of repeating the process of the first step to at least one time while varying the source gas, and further comprising the fifth After the step, based on the information about the plasma uniformity in the chamber detected by the in-situ plasma diagnostic system, the controller further comprises a sixth step of adjusting the variable capacitor provides a plasma uniformity control method. .

Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, in which like reference numerals will be used to refer to like parts only.

3 is a configuration diagram of an inductively coupled plasma generator according to the present invention, FIG. 4 is a schematic diagram of an antenna related to the inductively coupled plasma generator according to the present invention, and FIG. 5 is an inductively coupled plasma generator according to the present invention. The schematic diagram of controlling the plasma uniformity in the apparatus is shown.

An inductively coupled plasma generator according to the present invention includes a chamber 200 having a predetermined volume and including an exhaust hole, and a gas injection unit positioned above the chamber 200 and introducing a source gas into the chamber 200. 210, an antenna 220 to which the source power is applied, and an electrostatic chuck 290 to which the bias power is applied while fixing the substrate W.

The antenna 220 includes a sensor unit 230, a source high frequency oscillator 280 for applying a source power source, and a source impedance match for matching a load impedance to a characteristic impedance of a connection cable connected to the source high frequency oscillator 280. Circuits 270 are each connected.

4 shows two antennas 222 and 226 connected in parallel. The first antenna 222 inside is grounded at one end and the variable load capacitors CL and 223 and the source impedance matching circuit at the other end. 270, respectively, the second antenna 226 is positioned outside the first antenna 222, one end of which is grounded, and the other end of which is connected to the variable resonance capacitors CR and 227.

The sensor unit 230 includes a first sensor 234 connected to the first antenna 222 and a second sensor 232 connected to the second antenna 226, and the first and second sensors ( Each end of 234 and 232 is connected to the controller 240.

The first and second sensors 234 and 232 detect current values and applied voltage values flowing through the first and second antennas 222 and 226, and convert them into electrical output signals. Since the operation structure of the part may be implemented in a manner known in the art, a detailed description thereof will be omitted.

The controller 240 is connected to each of the first and second sensors 234 and 232 and the variable resonant capacitor 227 connected to the other end of the second antenna 226, and the first and second sensors 234 and 232. It stores a signal transmitted from 232 and controls the variable resonant capacitor 227 based on the stored signal.

The controller 240 is a conventional CPU or computer with storage and control functions.

In addition, the controller 240 may further include a neural network controller (Neural Network, 250), the neural network algorithm is included in the neural network controller 250, the controller 240 is a control signal of the neural network controller 250 As a result, the resonant variable capacitor 227 is in charge of the function.

In addition, the controller 240 may further include an in-situ plasma diagnostic system 260, and the in-situ plasma diagnostic system 260 may be configured to supply plasma to each source gas generated in the chamber 200. The uniformity of the plasma is measured using a probe or a microwave interferometer, and the variable resonant capacitor 227 is controlled to work with the controller 240 so that the plasma has an optimal uniformity.

Although not shown in the drawing, the electrostatic chuck 290 includes a bias high frequency oscillator for applying a high frequency bias power source, and a bias impedance matching circuit for matching the load impedance to a characteristic impedance of a connection cable connected to the bias high frequency oscillator. Of course each is connected.

Here, an antenna having two turns is shown, but it is also possible to have three or more turns. In this case, the variable resonant capacitors CR and 227 are connected to the outermost antenna. In parallel with each other, one end is grounded, and the other end is connected to the variable load capacitors CL and 223 and the source impedance matching circuit 270. In this case, the sensor unit 230 must also be connected for each antenna. When a plurality of antennas are installed, it is preferable to be located on the same plane, but is not necessarily limited thereto.

In this case, however, it is not an absolute method to connect the variable resonant capacitors CR and 227 only to the outermost antennas. Therefore, the variable resonant capacitors CR and 227 may be connected to any of a plurality of antennas, and the remaining antennas may be connected in parallel. Of course, it is possible to connect.

An operation configuration of the inductively coupled plasma generating apparatus according to the present invention having the above configuration will be described in detail with reference to FIGS. 3 to 5.

First, when the test substrate W is placed on the electrostatic chuck 290 and power is applied to the electrostatic chuck 290 from a power supply unit (not shown), the substrate is mounted and fixed to the electrostatic chuck 290 by electrostatic power. .

When the substrate is fixed to the electrostatic chuck 290, a first source gas used for etching the actual substrate is injected from the gas injector 210 above the chamber 200 into the chamber 200, and at the same time, the electrostatic chuck 290 ) Is applied to the bias power source and the antenna power source to the antenna 220, and then the resonance variable capacitor 227 of the antenna 220 is adjusted to plasma the first source gas injected into the chamber 200. To a plasma state with optimum uniformity.

When the plasma of the first source gas has an optimal uniformity, the first and second sensors 234 and 232 may control the current value and the applied voltage value flowing through each of the first and second antennas 222 and 226. In step S10, the controller 240 designates each current and voltage value sent as a specific value of the first source gas and stores the same.

When the etching process for the first source gas is completed, the second, third, different to be used for etching the actual substrate. . . Injecting the source gases into the chamber 200 in order and performing current and voltage values of the first and second sensors for the respective source gases in the same manner as the process performed for the first source gas. Specifying a specific value repeatedly stores the controller 240.

Although there is no order in spraying a plurality of source gases into the chamber 200, it is obvious that the plurality of source gases to be sprayed is limited to the source gases used in the etching process for the actual substrate.

This process can be repeated and used in the etching process for the actual substrate, and when the current and voltage values are stored in the controller 240 in order when each source gas has an optimal plasma uniformity in the chamber 200, The preliminary step of the inductively coupled plasma generator according to the invention is completed.

When a specific value of source gases that can be injected and used into the chamber is stored according to the preliminary step as described above, the actual substrate is placed in the electrostatic chuck 290 and any source gas (specific value is given to the controller in the preliminary step). In performing the etching process using one of the stored source gases, hereinafter referred to as A, the variable resonant capacitor 227 reads the information stored in the controller 240 with respect to the source gas A. As long as the controller 240 controls the variable resonant capacitor 227 to be adjusted to a value corresponding to S20, the source gas A inside the chamber 200 becomes a plasma state having an optimum uniformity. The etching process can be performed.

On the other hand, when using the neural network controller 250, the optimum value of the plasma uniformity for the source gas to be sprayed by the neural network algorithm embedded in the neural network controller 250 is extracted, the extracted value is the neural network controller ( When the controller 240 transmits the signal to the controller 240, the controller 240 controls the resonance variable capacitor 227 accordingly to adjust the plasma uniformity of the source gas in the chamber (S30 and S10).

In addition, when the plasma uniformity of the source gas is adjusted using the in-situ plasma diagnostic system 260, the in-situ plasma diagnostic system 260 is interlocked with the controller 240 to provide the inside of the chamber 200. By periodically measuring the plasma uniformity of the plasma 200, the controller 240 appropriately controls the variable resonant capacitor 227 so that the plasma in the chamber 200 has an optimal uniformity. It can be adjusted (S30 and S10).

As such, when the neural network controller 250 and the in-situ plasma diagnostic system 260 are used, the plasma uniformity of the source gases injected into the chamber 200 may be automatically maintained in an optimal state.

In the above description, but limited to the preferred embodiment of the present invention as an example, the true scope of the present invention should be interpreted by the technical spirit described in the claims.

The present invention stores in advance a value when a plurality of source gases that can be used for etching a substrate have an optimal plasma uniformity in the chamber, and uses the pre-stored value when performing etching on an actual substrate. By allowing the to have an optimal plasma uniformity, it is possible to easily maintain the inside of the chamber in an optimal plasma uniformity state.

In addition, the present invention enables the control of the plasma uniformity of each source gas injected into the chamber by adding a neural network control unit or an in-situ plasma diagnostic system to realize a more improved plasma generator.

Claims (7)

A chamber having an electrostatic chuck on which the substrate is placed; A high frequency power supply for applying power; A gas injector for injecting a source gas into the chamber; A plurality of antennas receiving power from the high frequency power source and connected in parallel to each other and positioned on an upper end of the gas injection unit; A plurality of sensors each connected to the antenna; A variable capacitor connected between one of the antennas and a corresponding sensor; A controller connected to the plurality of sensors and the variable capacitor, receiving and storing measurement values from the plurality of sensors, and controlling the variable capacitor. Inductively coupled plasma generating device comprising a. The method of claim 1, Inductively coupled plasma generating device further comprising a neural network control unit connected to the controller. The method of claim 1, And an in-situ plasma diagnostic system coupled to the controller. The method according to any one of claims 1 to 3, And the variable capacitor is connected between an outermost antenna and a sensor corresponding thereto. A first step of injecting any source gas into the chamber through the gas injector; Applying a high frequency source power to an antenna to discharge the source gas into plasma; Adjusting a variable capacitor connected to an antenna to optimally adjust the uniformity of the plasma; A fourth step of measuring a current and voltage value of the antenna through a sensor, inputting and storing the controller when the plasma uniformity is optimal; A fifth step of adjusting, by the controller, a variable capacitor connected to the antenna based on information stored therein when the same source gas as the source gas is injected into the chamber again; Uniformity control method of plasma comprising The method of claim 5, Before the fifth step, the method of controlling the uniformity of the plasma further comprising the step of repeating the process of the first to fourth steps at least once while varying the source gas. The method according to claim 5 or 6, After the fifth step, based on the information about the plasma uniformity in the chamber detected by the in-situ plasma diagnostic system, the controller further comprises a sixth step of adjusting the variable capacitor;