TWI545285B - A gas supply device and a plasma reaction device - Google Patents

Description

Gas supply device and plasma reaction device thereof

The invention relates to the technical field of plasma processing, and in particular to the technical field of rapid gas supply of a plasma reaction device.

Plasma reaction devices are widely used in the manufacturing process of integrated circuits, such as deposition, etching, and the like. Among them, the commonly used plasma reaction device includes a capacitive coupling type plasma reaction device CCP and an inductively coupled plasma device ICP. The principle of the plasma reaction device mainly uses the RF power to dissociate the reaction gas input into the reaction device into a plasma. The plasma placed on the inside of the substrate is plasma-etched by the plasma, and the reaction gases required by different etching processes are not the same.

For example, in the tantalum via etching process, since the depth of the via hole to be etched is large, in order to effectively perform etching, the following steps are often used for etching: first, etching step, in plasma reaction An etching gas is introduced into the cavity to perform via etching on the surface of the germanium substrate. Second, in the polymer deposition step, a deposition gas is introduced into the plasma reaction chamber, and the deposition gas is deposited on the sidewall of the via hole to form sidewall protection. The etching step and the deposition step are alternated until the via etching is completed. The method is characterized in that it can etch a deeper pupil, but since the etching step and the deposition step are alternately performed, a scalloped rough surface is formed on the sidewall, which adversely affects the subsequent process of the pupil, so that the flaw is ensured. The pass rate of the hole etch requires that the rough surface of the sidewall of the boring is as small as possible, and the smoother the better. It is conceivable that a method of reducing the scalloped rough surface of the pupil side wall The equation is to increase the alternating frequency of the etching step and the deposition step, and reduce the time required for each step of etching and deposition, however, as the required time decreases, the instability and uncertainty of various parameters in the plasma reactor Sex comes with it. When the time interval between the etching step and the deposition step is less than 1 s, the gas flow control valve MFC that supplies the reaction gas to the plasma reactor becomes a bottleneck, and the MFC cannot achieve such a rapid switching. If the alternate time of the etching step and the deposition step is less than 0.5 s, the MFC will not be able to meet the requirements of the reaction device, making the entire etching process unstable, and the process result cannot be guaranteed to be repeatable and controllable. Therefore, the rapid switching of different reaction gases and timely delivery to the plasma processing apparatus is an urgent problem to be solved in the current through-hole etching.

In another application, in order to ensure the smooth progress of the etching process, the RF power needs to be set to pulse output, that is, the RF power is set to a high level output and a low level output (may be 0), in order to avoid waste of reaction gas. The reaction gas can be input into the reaction chamber only when the RF power is a high level output. Since the pulse frequency of the RF power is large, a faster device is required to turn off and transport the reaction gas.

In order to solve the above technical problem, the present invention provides a gas supply device, the device comprising a reactive gas source, the reactive gas source is connected to a gas memory through a first control valve, and the gas memory is connected to a pressure measuring device. The gas reservoir delivers the reactive gas into the vacuum reaction chamber through a second control valve.

Preferably, a flow rate control device is disposed at the outlet of the gas memory, and the flow rate control device controls a flow rate of gas in the gas memory into the vacuum reaction chamber.

Preferably, the gas memory is connected to an air outlet through a third control valve for regulating the pressure in the gas memory.

Preferably, a fourth control valve is disposed between the source of the reactive gas and the first control valve, and the fourth control valve is connected to an air pump through a gas pipeline.

Further, the present invention also discloses a plasma reaction apparatus comprising a vacuum reaction chamber, wherein a susceptor for placing a substrate is disposed in the vacuum reaction chamber, the susceptor is connected to a radio frequency power source, and the vacuum reaction chamber A gas supply device is disposed outside, the gas supply device includes a source of reactive gas, the reaction gas source is connected to a gas memory through a first control valve, and the gas memory is connected to a pressure measuring device, the gas memory The reaction gas is discontinuously delivered into the vacuum reaction chamber through the second control valve.

Preferably, the output of the RF power source is a pulse output, and the pulse output includes two states of a high level output and a low level output, and the reactive gas inputs the vacuum reaction when the pulse output is at a high level. The cavity stops inputting the vacuum reaction chamber when the pulse output is low.

Preferably, when the output of the RF power source is a low level, the low level may be 0.

Preferably, the vacuum reaction chamber may be connected to two or more sets of gas supply devices.

Preferably, two sets of gas supply devices are disposed outside the reaction chamber, the reaction gas source of the one group of gas supply devices transports the etching reaction gas to the gas storage device, and the reaction gas source direction of the other group of gas supply devices The corresponding gas memory transports a deposition reaction gas, and the etching reaction gas and the deposition reaction gas are alternately injected into the vacuum reaction chamber.

Preferably, the etching reaction gas comprises one or more of CF4, O2, SF6 or Ar, and the deposition reaction gas comprises one or more of C4F8, argon and helium.

Preferably, the etching reaction gas and the deposition reaction gas alternate for less than or equal to 1 s.

Preferably, the etching reaction gas and the deposition reaction gas alternate for less than or equal to 0.4 s.

An advantage of the present invention is that the gas supply device includes a reactive gas The source gas is connected to a gas memory through a first control valve, and the gas memory is connected to a pressure measuring device, and the gas memory delivers the reaction gas into the vacuum reaction chamber through the second control valve. The use of a fixed volume of gas memory allows easy and precise control of the flow of gas into the reaction chamber by monitoring its internal pressure. At the same time, the use of control valves can quickly achieve gas reservoir inflation and deflation, improving traditional technology. The scallop-like rough surface on the sidewall of the through-hole is severe due to the gas switching rate caused by the flow control device MFC, and the waste of the reaction gas when the RF power is pulsed.

10‧‧‧ gas supply unit

11‧‧‧First control valve

12‧‧‧Second control valve

13‧‧‧ Third control valve

14‧‧‧fourth control valve

20‧‧‧Reactive gas source

30‧‧‧ Vents

40‧‧‧ Pressure measuring device

50‧‧‧ gas memory

55‧‧‧Flow rate control device

60‧‧‧Air pump

100‧‧‧vacuum reaction chamber

105‧‧‧reaction chamber sidewall

110‧‧‧Base

115‧‧‧Electrostatic chuck

120‧‧‧Substrate

125‧‧‧Exhaust pump

130‧‧‧Insulated window

140‧‧‧Inductive Coupling Coil

145‧‧‧RF power source

150‧‧‧ gas injection

160‧‧‧ Plasma

200‧‧‧vacuum reaction chamber

215‧‧‧Electrostatic chuck

220‧‧‧Base

225‧‧‧Exhaust pump

245‧‧‧RF power source

250‧‧‧ gas sprinkler

260‧‧‧ plasma

Fig. 1 is a schematic view showing the structure of an inductively coupled plasma reactor.

Fig. 2 is a schematic view of the gas supply device of the present invention.

Figure 3 is a schematic view of the gas supply device according to another embodiment of the present invention.

Fig. 4 is a schematic view showing the structure of a capacitive coupling type plasma reactor.

The invention discloses a gas supply device and a plasma reaction there The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

1 is a schematic structural view of an inductively coupled plasma reactor including a vacuum reaction chamber 100 including a substantially cylindrical reaction chamber sidewall 105 made of a metal material, the reaction An insulating window 130 is disposed above the sidewall of the cavity 105. An inductive coupling coil 140 is disposed above the insulating window 130, and the inductive coupling coil 140 is connected to the RF power source 145. A gas injection port 150 is disposed at one end of the reaction chamber side wall 105 near the insulating window 130, and the gas injection port 150 is connected to the gas supply device 10. The reaction gas in the gas supply device 10 enters the vacuum reaction chamber 100 through the gas injection port 150, and the RF power of the RF power source 145 drives the inductive coupling coil 140 to generate a strong high-frequency alternating magnetic field, so that the low-pressure reaction gas is ionized to generate plasma. Body 160. A susceptor 110 is disposed at a position downstream of the vacuum reaction chamber 100, and an electrostatic chuck 115 is placed on the susceptor 110 for supporting and fixing the substrate 120. The plasma 160 contains a large amount of active particles such as electrons, ions, excited atoms, molecules, and radicals, and the active particles can undergo various physical and chemical reactions with the surface of the substrate to be processed, so that the surface morphology of the substrate occurs. Change, that is, complete the etching process. An exhaust pump 125 is also disposed below the vacuum reaction chamber 100 for discharging reaction by-products into the vacuum reaction chamber.

In the embodiment shown in FIG. 1, the substrate 120 is made of germanium material, and the etching process performed in the reaction chamber is a germanium via etching process, which is also called a TSV etching process. The etching process is characterized in that the depth of the through hole to be etched is large, in order to avoid bending of the shape of the through hole during the etching process, and ensuring that the through hole of the etching meets the requirements, an etching method commonly used at present It is called Bosch Craft. The Bosch process consists of two steps. First, an etching step is performed by introducing an etching gas into the vacuum reaction chamber to perform via etching on the surface of the germanium substrate. Second, a polymer deposition step is performed in the vacuum reaction chamber. A deposition gas is introduced, and the deposition gas is deposited on the sidewall of the via to form sidewall protection. The etching step and the deposition step are alternated until the via etching is completed. The method is characterized in that it can etch a deeper pupil, but since the etching step and the deposition step are alternately performed, a scallop-like rough surface is formed at alternate portions of the sidewalls, which adversely affects the subsequent process of the pupil. In order to ensure the pass rate of the pupil etching, the rough surface of the sidewall of the pupil needs to be as small as possible, and the smoother the better. It is conceivable that a way to reduce the scalloped rough surface of the pupil sidewall is to increase the alternating frequency of the etching step and the deposition step, and to reduce the time required for each etching step and deposition step, however, as the required time decreases, the plasma The instability and uncertainty of various parameters in the bulk reaction device are followed. When the time interval between the etching step and the deposition step is less than 1 s, the gas flow control valve MFC that supplies the reaction gas to the vacuum reaction chamber becomes a bottleneck, and the MFC cannot achieve such a rapid switching. If the alternate time of the etching step and the deposition step is less than 0.5 s, the MFC will not be able to meet the requirements of the reaction device, making the entire etching process unstable, and the process result cannot be guaranteed to be repeatable and controllable. To this end, the present invention employs the gas supply device 10 shown in Fig. 2.

2 shows a gas supply device 10 according to the present invention, comprising a reaction gas source 20 in which a reaction gas source stores one or more reaction gases required for the reaction, and the reaction gas source 20 is connected through a first control valve 11 The gas memory 50 has a fixed capacity of the gas memory 50, and the gas memory 50 is connected to a pressure measuring device 40. The pressure measuring device 40 can calculate the gas volume in the gas memory 50 based on the measured pressure, when the gas memory is used. When the gas in 50 reaches a predetermined capacity, the gas memory 50 delivers the reaction gas through the second control valve 12 to the vacuum reaction chamber 100 of the plasma reactor. The working principle of the gas supply device of the present embodiment is based on the gas state equation PV=nRT, where P is the gas pressure, V is the gas volume, n is the gas species, R is the gas constant, and T is the temperature. Prerequisites for determining the type of gas Next, n and R are fixed values. Therefore, the gas volume V in the gas memory 50 can be calculated based on the measured pressure in the gas memory 50, and the gas in the reaction gas source 20 passes through the first control valve 11 to react. When the gas is delivered into the gas memory 50, the pressure measuring device 40 monitors the pressure in the gas memory, and when the preset pressure is reached, the first control valve 11 is closed, and the delivery of the reaction gas to the gas memory 50 is stopped. At the time, a predetermined volume of the reaction gas is stored in the gas memory 50.

The volume in the gas reservoir 50 can be set according to the needs of the vacuum reaction chamber. In the inductively coupled plasma reaction chamber of the embodiment, since the alternate injection of the etching gas and the deposition gas is required, the vacuum reaction chamber 100 of the present embodiment connects at least two sets of gas supply devices shown in FIG. . The corresponding etching gas source 20 stores the etching gas required for the etching reaction and the deposition gas required for the deposition reaction, respectively. For convenience of description, in the present embodiment, the first group of gas supply devices and the second group of gas supply devices are selected to provide etching gas and deposition gas, respectively. The specific working process is: firstly opening the first control valve 11 of the first group of gas supply devices to inflate the gas memory 50 with the etching gas, and after the etching gas reaches the preset volume, the first control valve 11 is closed, and the second is opened. The control valve 12 injects an etching gas into the vacuum reaction chamber to perform an etching reaction step; at the same time, the second group of gas supply devices inflates the deposition gas of the gas memory 50, and closes the first group of gas supply when the etching step is completed. The control valve 12 of the device opens the first control valve 11 for re-inflation, while simultaneously opening the control valve 12 of the second group of gas supply devices to inject the deposition gas into the vacuum reaction chamber 100 for the deposition reaction step, thus alternating. The etching gas includes one or more of CF ₄ , O ₂ , SF 6 or Ar, and the deposition gas includes one or more of C ₄ F ₈ , argon gas, and helium gas. The etching gas and the deposition gas alternate for less than or equal to 1 s. Preferably, the etching gas and the deposition gas alternate for less than or equal to 0.4 s.

Since the invention adopts the volume-fixed gas memory 50, the flow of the gas into the vacuum reaction chamber can be conveniently and accurately controlled by monitoring the internal pressure thereof, and at the same time, the inflation and discharge of the gas memory 50 can be quickly realized by using the control valve. The gas improves the problem that the scalloped rough surface on the sidewall of the through hole is severe due to the gas switching rate caused by the flow control device MFC in the conventional technology. In order to better control the flow rate of the gas in the gas reservoir 50 into the vacuum reaction chamber 100, a flow rate control device 55 may be provided at the outlet of the gas memory 50, which ensures the gas reservoir 50. The gas enters the vacuum reaction chamber uniformly according to the requirements of the process in the reaction chamber or according to a certain rule, which is beneficial to realize the smooth progress of the etching process.

Figure 3 shows a schematic diagram of the structure of an optimized gas supply device. Considering the temperature change in the environment in which the gas memory is located, according to the gas state equation: PV = nRT, the change in temperature may result in gas pressure in the gas memory and The ratio of the gas volume changes, so in order to balance the pressure and gas volume in the gas memory, an air outlet 30 can be disposed on the gas memory 50, and the air outlet 30 is connected to the gas memory 50 through the third control valve 13 for Adjust the pressure in the gas memory. The air outlet 30 can be connected to an air pump 60. In some embodiments, the same set of reactive gas supply devices 10 can deliver a plurality of different gases or combinations of gases. In order to ensure that the last delivered gas does not cause pollution and interference to the next gas, the reactive gas source 20 and A fourth control valve 14 is disposed between the control valves 11, and the fourth control valve 14 is connected to an air pump 60 through a gas pipeline. After the last gas delivery is completed, the first control valve 11 and the fourth control valve 14 are opened, and the gas supply device and the residual gas in the gas storage body 50 are quickly exhausted from the gas supply device through the air pump, and then the fourth device is turned off. The valve 14 is controlled to perform the next gas delivery.

4 is a schematic structural view of a capacitive coupling type plasma reactor according to the present invention, including a vacuum reaction chamber 200. A susceptor 220 is disposed in the vacuum reaction chamber, and an electrostatic chuck 215 is disposed above the susceptor for the substrate above it. 220 is supported and fixed, and a gas shower head 250 is disposed above the substrate for uniformly injecting the reaction gas in the gas supply device into the vacuum reaction chamber 200. The susceptor 220 and the gas shower head 250 simultaneously serve as a lower electrode and an upper electrode of the plasma processing apparatus. The susceptor 220 is connected to the RF power source 245, and the RF power is applied to the susceptor 220, and the reaction gas is dissociated under the action of the upper and lower electrodes. The plasma 260, the plasma 260 acts on the substrate 220 to complete the etching process. An exhaust pump 225 is disposed below the vacuum reaction chamber 200 for discharging reaction by-products in the vacuum reaction chamber. In the capacitive coupling type plasma reactor of the present embodiment, the reaction gas is usually continuously injected into the vacuum reaction chamber. In other applications, in order to ensure the etching effect, the output of the RF power source 245 is a pulse output, and the pulse output may be an output of alternating high and low levels, or an output of alternating on and off, usually If the output of the RF power source is low or off, the reaction gas is usually not plasma dissociated in the reaction chamber. At this time, if the reaction gas source is continuously injected into the plasma reaction chamber, it will be directly exhausted by the exhaust pump 225. The plasma reaction chamber is discharged. Therefore, the gas shower head can be connected to the gas supply device 10 of the present invention.

The gas supply device 10 of the present invention is described in detail in both FIG. 2 and FIG. 3, and can be referred to the above description, and will not be further described herein. When the output of the RF power source is a pulse output, the gas supply device 10 cooperates with the pulse output of the RF power to supply the reaction gas only when the RF output is at a high level, and does not react to the vacuum when the RF output is at a low level or in an off state. A reaction gas is supplied in the chamber 200. By adopting the gas supply device of the invention, nearly half of the reaction gas can be saved, that is, the raw material is saved, the cost is reduced, and the treatment reverse is also reduced. At the cost of the gas, harmful gases are prevented from entering the air and polluting the environment.

The present invention is disclosed in the above preferred embodiments, but it is not intended to limit the present invention, and any one skilled in the art can make possible variations and modifications without departing from the spirit and scope of the invention. The scope of protection should be determined by the scope defined by the claims of the present invention.

11‧‧‧First control valve

12‧‧‧Second control valve

20‧‧‧Reactive gas source

40‧‧‧ Pressure measuring device

50‧‧‧ gas memory

55‧‧‧Flow rate control device

100‧‧‧vacuum reaction chamber

Claims (9)

A gas supply system includes a first gas supply device and a second gas supply device, wherein the first gas supply device and the second gas supply device each comprise a reactive gas source, a first control valve a second control valve, and a gas memory, the reactive gas source is connected to the gas memory through the first control valve, the gas memory is connected to a pressure measuring device, and the gas memory is passed through The second control valve delivers the reaction gas into a vacuum reaction chamber, wherein the first control valve of the first gas supply device performs an etching gas on the gas memory of the first gas supply device After inflating, after the etching gas reaches a preset volume, closing the first control valve of the first gas supply device, opening the second control valve of the first gas supply device to etch the gas Injecting the vacuum reaction chamber to perform an etching reaction step; at the same time, opening the first control valve of the second gas supply device to the second gas The gas memory of the supply device performs inflation of a deposition gas, and when the etching step is finished, closing the second control valve of the first gas supply device, opening the first of the first gas supply device The control valve is re-inflated while the second control valve of the second gas supply is opened to inject a deposition gas into the vacuum reaction chamber for a deposition reaction step. The gas supply device according to claim 1, characterized in that: at the outlet of the gas memory, a flow rate control device is provided, and the flow rate control device controls the gas in the gas memory to enter the vacuum The flow rate in the reaction chamber. The gas supply device according to claim 1, wherein the gas storage body is connected to an air outlet through a third control valve for regulating the pressure in the gas memory. The gas supply device according to claim 1, wherein the reaction gas is A fourth control valve is disposed between the body source and the first control valve, and the fourth control valve is connected to an air pump through a gas pipeline. A plasma reaction device includes a vacuum reaction chamber, a susceptor for placing a substrate is disposed in the vacuum reaction chamber, and the susceptor is connected to a radio frequency power source, wherein: a gas is disposed outside the vacuum reaction chamber a supply system, the gas supply system comprising a first gas supply device and a second gas supply device, the first gas supply gas supply device and the second gas supply device each comprising a reactive gas source, a first control valve a second control valve, and a gas memory, the reactive gas source is connected to the gas memory through the first control valve, the gas memory is connected to a pressure measuring device, and the gas memory is passed through The second control valve sends the reaction gas discontinuously into a vacuum reaction chamber, wherein the first control valve of the first gas supply device performs a moment on the gas memory of the first gas supply device Inflating the etching gas, after the etching gas reaches a preset volume, closing the first control valve of the first gas supply device, opening The second control valve of the first gas supply device injects the etching gas into the vacuum reaction chamber to perform an etching reaction step; at the same time, opening the first control valve of the second gas supply device Performing a gas filling of the deposition gas on the gas storage device of the second gas supply device, and closing the second control valve of the first gas supply device after the etching step is finished, opening the first gas supply The first control valve of the device is re-inflated while the second control valve of the second gas supply device is opened to inject a deposition gas into the vacuum reaction chamber for a deposition reaction step. A plasma reaction apparatus according to claim 5, wherein the output of the RF power source is a pulse output, and the pulse output comprises a high level output and a low level. Two states are output, the reaction gas is input to the vacuum reaction chamber when the pulse output is at a high level, and the vacuum reaction chamber is stopped when the pulse output is at a low level. A plasma reaction apparatus according to claim 6 is characterized in that, when the output of the RF power source is at a low level, the low level may be zero. A plasma reactor according to claim 7 is characterized in that the etching reaction gas and the deposition reaction gas have an alternate time of less than or equal to 1 s. A plasma reaction apparatus according to claim 7 is characterized in that the etching reaction gas and the deposition reaction gas have an alternate time of 0.4 s or less.