TWI590291B - A gas supply device and a - 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 order to solve the above technical problem, the present invention provides a gas supply device, the device includes an etching gas source and a deposition gas source, and the etching gas source and the deposition gas source are respectively connected with a gas flow control device at a rear end thereof. The back end of the gas flow control device is respectively connected with two control valves, one control valve of each gas flow control device is connected to one exhaust device, and the other control valve is connected to the vacuum reaction chamber, and the flow control device can be less than 1 Open, close, or switch between low gas flow state and high gas flow state in seconds.

Preferably, the etching gas source and the back end of the deposition gas source are respectively connected to the gas flow control device through a control valve.

Preferably, each of the gas flow control devices has different gas flow rates for switching between two adjacent outputs.

Preferably, the two control valves connected to the rear end of each gas flow control device are alternately opened and closed, and the alternate frequency thereof is greater than or equal to the switching frequency of the gas flow control device.

Preferably, when the two control valves connected to the vacuum reaction chamber are opened, the flow rate of the gas flowing through the gas flow control device is greater than the flow rate of the gas flowing through the gas flow control device when the two control valves connected to the exhaust device are opened.

Preferably, the gas flow control device is a CMOS induction gas flow control device.

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 an etch gas source and a deposition gas source, and the etch gas source and the back end of the deposition gas source are respectively connected to a gas flow control device, and the gas flow control device Two control valves are respectively connected to the rear end of the device, one control valve of each gas flow control device is connected to one exhaust device, and the other control valve is connected to the vacuum reaction chamber, and the etching gas and the deposition gas are at the flow rate. The vacuum reaction chamber is alternately injected under the switching of the control device, and the alternate time of the etching gas and the deposition gas is less than 1 second.

Preferably, the plasma reaction device performs an etching process and a deposition process, wherein the gas flow control device connected to the etching gas source during the etching process is in a high gas flow state, and the gas flow control device connected to the deposition gas source is The low gas flow state; the gas flow control device connected to the deposition gas source during the deposition process is in a high gas flow state, and the gas flow control device connected to the etching gas source is in a low gas flow state.

Preferably, the percentage of the etching gas and the deposition gas in the low gas flow state in the high gas flow state may be 5% or less.

Preferably, the plasma reaction device includes an exhaust pump, and the exhaust device Connected to the exhaust pump.

Preferably, the etching reaction gas and the deposition reaction gas alternate for less than or equal to 0.5 s.

An advantage of the present invention is that the gas supply device includes an etch gas source and a deposition gas source, and the etch gas source and the deposition gas source are respectively connected to a gas flow control device at a rear end thereof, preferably The gas flow control device is a CMOS induction gas flow control device, which can realize switching of high and low gas flow rates within 1 s. The gas flow control device is connected with two control valves at the rear end, and one control valve of each gas flow control device is connected to one row. The gas device is connected to the vacuum reaction chamber. By adopting the technical solution, not only the reaction gas surge and delay caused by frequent switching of the MFC can be effectively filtered out, but also the reaction gas discharged into the exhaust device 20 can be greatly saved, and nearly half of the reaction gas is saved compared with the prior art. Effectively improve the utilization rate of raw materials in the etching process.

10‧‧‧ gas supply unit

13-18‧‧‧Control valve

20‧‧‧Exhaust device

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

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 diagram of the pulse of the etching gas and deposition gas entering the vacuum reaction chamber under ideal conditions.

Figure 4 is a schematic diagram of the pulse of the MFC output etching gas and deposition gas in actual operation.

The present invention has been disclosed in detail with reference to the accompanying drawings and embodiments. instruction of.

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 crucible substrate. Second, a polymer deposition step is performed in the vacuum reaction chamber. A deposition gas is deposited on the sidewalls of the vias to form sidewall protection. The etching step and the deposition step are alternated until the via etching is completed. The feature of this method is that it can be etched deeper The pupil, but due to the etching step and the deposition step alternately, a scalloped rough surface is formed at the alternate side walls, which adversely affects the subsequent process of the pupil, so in order to ensure the pass rate of the pupil etching, it is required The smaller the rough surface of the pupil side wall, the better, 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 conventional MFC cannot achieve rapid switching, so that the reaction is always in a normally open state. The two control valves connected at the back end control the gas in the reaction gas source to alternately enter the vacuum reaction chamber or the exhaust device. The biggest disadvantage of adopting the technical solution is that the reaction gas remains normally open, and half of the etching gas and the deposition gas are It is discharged to the exhaust device and wastes a lot.

2 shows a gas supply device 10 according to the present invention. Since the etching process of the present invention is a TSV etching process, the gas supply device 10 includes an etching gas source 5 and a deposition gas source 6, and an etching gas source. 5 and the deposition gas source 6 are respectively connected to a gas flow control device MFC11 and MFC12 through a control valve 17 and a control valve 18, and the rear end of the MFC 11 is connected to the control valve 13 and the control valve 14, wherein the control valve 13 controls the etching gas into the vacuum reaction chamber. 100, the control valve 14 controls the etching gas into the exhaust device 20; the rear end of the MFC 12 is connected to the control valve 15 and the control valve 16, wherein the control valve 16 controls the deposition gas to enter the vacuum reaction chamber 100, and the control valve 15 controls the deposition gas into the exhaust device. 20. In this embodiment, the MFC 11 and the MFC 12 are CMOS inductive flow control devices, which can realize switching of on/off or high flow and low flow in 1 s. However, in actual work, it is found that the CMOS inductive flow control device is turned on and off. Or high In the flow rate and low flow switching process, the ideal pulse gas as shown in Fig. 3 cannot be generated, but there is a surge in the gas flow rate at the start of the start, and the gas cannot be disconnected immediately when the gas flow rate is turned off or lowered, as shown in Fig. 4. It shows that when the etching gas and the deposition gas are switched, the amount of gas higher than the required gas enters the vacuum reaction chamber, and another reaction gas is mixed in the vacuum reaction chamber, which causes the TSV etching process to be uncontrollable, affecting the engraving. The etch process went smoothly.

The focus of the present invention is to provide two control valves at the rear end of the CMOS inductive flow control device. The two control valves can filter the surge and delay of the gas switching to achieve the pulse output under ideal conditions as shown in FIG. In view of the extremely unstable gas output at the switching of the MFC opening and closing, this embodiment employs switching the MFC between a high flow gas output and a low flow gas output. The specific working principle is: in the etching step, the MFC 11 is switched to a high gas flow state, and the etching gas in the etching gas source 5 enters the MFC 11 through the control valve 17, and the MFC 11 can accurately measure the flow rate of the etching gas flowing therethrough. The control valve 13 is opened, the control valve 14 is closed, and the etching gas enters the vacuum reaction chamber 100 through the control valve 13 to perform an etching reaction step. At this time, the MFC 12 is switched to a low gas flow state, and the control valve 15 at the rear end of the MFC 12 is opened to control the valve. 16 is closed, at which time low flow of deposition gas enters the exhaust unit 20 via the control valve 15. At the end of the etching step, the deposition step begins. At this time, the MFC 12 is adjusted to a high gas flow state, the control valve 15 is closed, the control valve 16 is opened, and the deposition gas is introduced from the deposition gas source 6 into the MFC 12 through the control valve 18, and the MFC 12 can accurately measure the flow therethrough. The deposition gas flow rate, the deposition gas required for the deposition reaction enters the vacuum reaction chamber 100 through the control valve 16 to complete the deposition reaction. At this time, the MFC 11 is adjusted to a low gas flow state, the control valve 13 is closed, the control valve 14 is opened, and the flow rate is low. The etching gas enters the exhaust device 20 via the control valve 14. In this embodiment, the percentage of the etching gas and the deposition gas in the low flow state may be less than the percentage of the etching gas and the deposition gas in the high flow state. At 5%, the technical solution can not only effectively filter out the reaction gas surge and delay caused by frequent switching of the MFC, but also greatly save the reaction gas discharged into the exhaust device 20, saving nearly half compared with the prior art. The reaction gas effectively improves the utilization rate of raw materials in the etching process.

The MFC rear-end valve can filter the MFC gas surge and delay. When the MFC switches to the high gas flow state, the control valve 13 and the control valve 16 connected to the vacuum reaction chamber are delayed for a certain time to open, such as a delay of 30 ms, avoiding the reaction gas. The surge state; before the MFC switches to the low gas flow state, the control valve 14 and the control valve 15 connected to the exhaust device 20 are opened for a certain time, for example, 30 ms, and the gas of the MFC delay period is discharged into the exhaust device 20, The unwanted reaction gas is prevented from entering the previous reaction step, affecting the progress of the etching reaction or the deposition reaction. The venting device 20 can be coupled to an exhaust pump 125 of the vacuum reaction chamber, along with the reaction by-products, to a subsequent exhaust gas treatment device (not shown).

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 0.5 s. By adopting the gas supply device of the invention, nearly half of the reaction gas can be saved, which not only saves the cost of the raw materials, but also reduces the cost of processing the reaction gas, avoids harmful gases entering the air, and pollutes 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.

10‧‧‧ gas supply unit

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

Claims (10)

A gas supply device, comprising: an etching gas source and a deposition gas source, wherein the etching gas source and the back end of the deposition gas source are respectively connected to a gas flow control device, the gas flow control Two control valves are respectively connected to the rear end of the device, one control valve of each gas flow control device is connected to one exhaust device, and the other control valve is connected to the vacuum reaction chamber, and the gas flow control device can be less than 1 second. Opening, closing, or switching of a low gas flow state and a high gas flow state; when the gas flow control device is switched to an open or high gas flow state, the control valve connected to the vacuum reaction chamber is opened after a delay, The surge state of the reaction gas is avoided; the control valve connected to the exhaust device is opened a certain time before the gas flow control device is switched to the closed or low gas flow state. The gas supply device of claim 1, wherein the etching gas source and the back end of the deposition gas source are respectively connected to the gas flow control device through a control valve. The gas supply device of claim 1, wherein: each of the gas flow control devices has a different gas flow rate that is switched between two adjacent switches. The gas supply device of claim 1, wherein: the two control valves connected to the rear end of each gas flow control device are alternately opened and closed, and the alternating frequency thereof is greater than or equal to the switching frequency of the gas flow control device. . The gas supply device of claim 1, wherein: when the two control valves connected to the vacuum reaction chamber are opened, the gas flow rate flowing through the gas flow control device is greater than the two control valves connected to the exhaust device are opened. The flow of gas through the gas flow control device. The gas supply device of claim 1, wherein the gas flow control device is a CMOS induction gas flow control device. 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 gas supply device comprising an etch gas source and a deposition gas source, wherein the etch gas source and the deposition gas source are respectively connected to a gas flow control device at a rear end thereof, and the gas flow control device has a back end respectively Connecting two control valves, one control valve of each gas flow control device is connected to one exhaust device, and the other control valve is connected to the vacuum reaction chamber, and the etching gas and the deposition gas are in the gas flow control device Alternatingly injecting the vacuum reaction chamber under switching, the alternating time of the etching gas and the deposition gas is less than 1 second; connecting the vacuum reaction chamber when the gas flow control device is switched to an open or high gas flow state The control valve is opened after a delay, avoiding the surge state of the reaction gas; when the gas flow control device is switched to The control valve connected to the venting device opens a certain amount of time in advance before closing or low gas flow conditions. The plasma reaction device of claim 7, wherein: the plasma reaction device performs an etching process and a deposition process, and the gas flow control device connected to the etching gas source during the etching process is a high gas. The flow state, the gas flow control device connected to the deposition gas source is a low gas flow state; the gas flow control device connected to the deposition gas source during the deposition process is a high gas flow state, and the gas flow control device connected to the etching gas source is Low gas flow status. The plasma reaction apparatus according to claim 8, wherein: the etching gas and the deposition gas in the low gas flow state occupy an etching gas and a deposition gas in a high gas flow state. The percentage can be less than or equal to 5%. The plasma reaction apparatus of claim 7, wherein the plasma reaction apparatus comprises an exhaust pump, and the exhaust apparatus is connected to the exhaust pump.