JP2000306887A - Method and apparatus of treating wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily maintain a constant gas flow rate in an etching apparatus for performing temporal modulation etching of a groove or hole with a high aspect ratio or the like, even in a transition period when types of gases supplied into a vacuum chamber are switched. SOLUTION: After flow rates of an etching gas and a deposition gas are controlled by their respective mass flow controllers 13a, 13b, total flow rate is controlled by a mass flow controller 17 attached to a pipe in which these gases are merged. Then, the gases are supplied into a vacuum chamber 1. Even when the etching gas and the deposition gas are switched, the gas flow rate is constant and there is no longer pressure fluctuation in the vacuum chamber 1, so that plasma does not become unstable, and roughness is not caused on an etching sidewall. Thus, a groove or hole with a high aspect ratio having a smooth sidewall can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate processing method such as time-modulated etching in which a process mainly comprising etching and a process mainly comprising deposition using plasma are repeated, and a substrate to be processed is etched by time-modulated etching. The present invention relates to a substrate processing apparatus such as an etching apparatus.

[0002]

2. Description of the Related Art In a dry etching technique in a semiconductor manufacturing process or a manufacturing process related thereto, one of the methods used for processing an opening having a high aspect ratio, for example, a deep groove or hole having an aspect ratio exceeding 10 is used. For example, time-modulated etching in which control parameters such as etching gas composition, gas pressure, and high-frequency power for generating plasma of an etching gas are changed a plurality of times during etching is used.

In the time-modulated etching, the control parameters as described above are set to the conditions of an etching mode in which the object to be etched can be positively etched in a certain time zone, and in another time zone, the object to be etched, especially during etching. The conditions of the deposition mode are such that the material constituting the object to be etched or a substance containing a part of the etching gas component is deposited on the side walls of the grooves and holes. Are alternately performed. In deposition mode,
Some film is deposited on the bottoms of the grooves and holes, but the material is preferentially deposited on the side walls. Then, when the mode is shifted to the etching mode, the etching is hardly performed in the horizontal direction due to the deposit on the side wall, but is etched only in the vertical direction. By repeating such a process, it is possible to form an opening (groove or hole) having a high aspect ratio in which the side wall is etched in a shape almost perpendicular to the bottom surface.

FIG. 3 shows an example of a conventional substrate processing apparatus.
3 shows a configuration of an etching apparatus that performs time-modulated etching. As shown in FIG. 3, an inductive coupling coil 4 is provided above a vacuum vessel 1 via a dielectric plate 5.
The substrate 6 as an object to be processed is placed on the electrode 7 in the inside, and while the etching gas is introduced into the vacuum vessel 1 from the gas inlet 14, the gas is exhausted by the turbo-molecular pump 11 as the exhaust means, and the pressure controller is released. At 10, the pressure is controlled to a predetermined value to generate plasma in the vacuum vessel 1. Thus, the substrate 6 placed on the electrode 7 or the film on the substrate 6 is etched. For plasma generation, high frequency power is applied to the inductive coupling coil 4 through the high frequency cable 15 by the high frequency power supply 2 for plasma generation, and the impedance of the inductive coupling coil 4 is matched to the characteristic impedance of the high frequency cable 15 by the matching controller 3. The electrode 7 has a high-frequency power supply 9 for applying an electrode.
Is configured to be able to apply high-frequency power via the high-frequency bias cable 16 and the matching controller 8, so that high-frequency power is always applied in both the etching mode and the deposition mode.

[0005] An etching gas (a gas having an etching property) used for an etching mode process is provided in the vacuum vessel 1.
Is introduced from the etching gas cylinder 12a via a mass flow controller 13a which is a gas flow controller, and a deposition gas (a gas having a deposition property) used for a deposition mode process is supplied from the deposition gas cylinder 12b through a mass flow controller 13b. And an entire etching process is performed. In addition, 2
Numerals 1 to 26 denote valves, and all the valves 21 to 26 are open when the etching apparatus is used.

[0006]

However, in the conventional time-modulated etching using the apparatus shown in FIG. 3, when switching between an etching gas mainly for etching and a deposition gas mainly for deposition, a mass flow is generally performed. Since the responses of the controllers 13a and 13b are sufficiently faster than the response of the pressure controller 10, the
The gas pressure in the chamber fluctuates greatly. Due to this, the impedance of the plasma rapidly changes, and the matching controller 3 for matching the impedance of the inductive coupling coil 4 to the characteristic impedance of the high-frequency cable 15 is used.
Cannot be followed, the plasma is once extinguished, matching is achieved, and plasma is generated again. For example, as shown in the cross-sectional view of the groove in FIG. Had. This roughening is considered to occur because gas ions are periodically scattered in the process of repeating the disappearance and generation of plasma, and the side walls are isotropically etched in a certain time zone. In addition,
FIG. 4 is a cross-sectional view when a film on a substrate is etched to form a groove.

Here, the gas pressure fluctuation in the vacuum vessel 1 in the time modulation etching will be described in more detail. During the etching process, the mass flow controllers 13a, 13
b, when the process is switched from the etching-based process to the deposition-based process, the gas supplied into the vacuum vessel 1 passes through a transition period that includes both the etching gas and the deposition gas, and conversely, the deposition gas-based process. When switching from the process to the process mainly including etching, the process passes through a transition period including both the etching gas and the deposition gas. FIG. 5 shows a time chart of the time-modulated etching after the transition time. In FIG. 5, gas A is an etching gas, and gas B is a deposition gas. When the step number (No) is an odd number, the step (E) is mainly etching, and when the step number (No) is an even number, the deposition is. This is the main step (D). T is a transition time at the time of gas switching.

In this method, independent mass flow controllers 13a and 13b are connected to the etching gas line and the deposition gas line, respectively.
The total flow rate of 13b is automatically supplied to the vacuum vessel 1. Although the transition time T in which the gas pressure is not so affected by the total flow rate is specified in specifications and the like as 0.5 to 2 seconds, the calculation method is not specified, and the transition time T is determined by an experimental method. Needs to be derived. That is, during the transition time T, it is necessary to precisely determine T such that the total flow rate of the etching gas flow rate and the deposition gas flow rate becomes substantially constant.

FIG. 6 shows a time chart when the transition time T is not optimal. 6, gas A is an etching gas, gas B is a deposition gas, and gas A
The flow rate of + gas B is the flow rate supplied to the vacuum vessel 1.
As shown in FIG. 6, when the transition time T is not optimal, the flow rate of the gas flowing into the vacuum vessel 1 varies, and the pressure variation in the vacuum vessel 1 increases. In such a case, as a method of keeping the pressure in the vacuum vessel 1 constant, a method of monitoring the pressure fluctuation in the vacuum vessel 1 at a certain transition time and feeding it back to the transition time of the next transition time has been conventionally considered. However, since the switching between the etching mode processing and the deposition mode processing is performed every few seconds, high speed and precise control feedback control of the transition time T is required within this time. However, this is a very difficult method because it includes the control time of the pressure controller 10 having a slow response speed for controlling the pressure in the vacuum vessel 1.

An object of the present invention is to easily maintain a constant flow rate of a gas supplied to a vacuum vessel even in a transition time for switching the type of gas supplied to the vacuum vessel by an etching apparatus for performing time-modulated etching. It is an object of the present invention to provide a method and apparatus for processing a substrate that can be performed.

[0011]

According to a first aspect of the present invention, there is provided a substrate processing method, wherein a plurality of different gases are controlled in a vacuum vessel having a substrate provided therein, independently and time-dependently. A substrate processing method for performing a predetermined process on a substrate by supplying and generating a gas plasma inside a vacuum vessel, wherein controlling a total flow rate of a plurality of different gases supplied into the vacuum vessel to a constant value. Features.

According to this method, by controlling the total flow rate of the gas supplied to the vacuum vessel to a constant value, the gas supplied to the vacuum vessel can be supplied even at the transition time when the type of gas supplied to the vacuum vessel is switched. Since the gas flow rate can be easily kept constant and the fluctuation of the gas pressure in the vacuum vessel can be suppressed, the extinction of the gas plasma due to the fluctuation of the gas pressure can be prevented.

According to a second aspect of the present invention, there is provided a method of processing a substrate, wherein a gas having an etching property and a gas having a deposition property are alternately temporally controlled in a vacuum vessel having a substrate installed therein by controlling respective flow rates. A substrate processing method in which etching is performed on a substrate by supplying gas so as to satisfy the conditions under which etching and deposition occur, and generating a gas plasma inside the vacuum container. And controlling the total flow rate of the deposition gas and the deposition gas to a constant value.

According to this method, by controlling the total flow rate of the gas supplied to the vacuum vessel to a constant value, the gas supplied to the vacuum vessel can be supplied even at the transition time when the type of the gas supplied to the vacuum vessel is switched. Since the gas flow rate can be easily kept constant and the fluctuation of the gas pressure in the vacuum vessel can be suppressed, the extinction of the gas plasma due to the fluctuation of the gas pressure can be prevented. Therefore, the disappearance and generation of plasma are not repeated, and the etching side wall is not roughened, and a groove or a hole having a smooth side wall and a high aspect ratio can be formed.

According to a third aspect of the present invention, there is provided a substrate processing apparatus, comprising: a vacuum vessel in which a substrate is placed; and a plurality of independent and time-dependent flow rates of a plurality of different gases supplied to the vacuum vessel. A first mass flow controller of
Means for generating gas plasma inside the vacuum vessel for performing a predetermined process on the substrate, wherein the flow rate is controlled by a plurality of first mass flow controllers and then supplied to the vacuum vessel. Before the start, at least one second mass flow controller for controlling the total flow rate of the plurality of different gases to a constant value is provided.

According to this configuration, by controlling the total flow rate of the gas supplied into the vacuum vessel to a constant value by the second mass flow controller, the transition time when the type of the gas supplied into the vacuum vessel is switched is changed. Can easily keep the gas flow supplied to the vacuum container constant,
Since the fluctuation of the gas pressure in the vacuum vessel can be suppressed, the extinction of the gas plasma due to the fluctuation of the gas pressure can be prevented.

According to a fourth aspect of the present invention, there is provided a substrate processing apparatus, comprising: a vacuum vessel in which a substrate is placed; and a gas having an etching property and a gas having a deposition property supplied to the vacuum vessel, each having a different flow rate. A substrate processing apparatus, comprising: a plurality of first mass flow controllers for controlling conditions under which etching and deposition occur alternately; and means for generating gas plasma inside a vacuum vessel for performing an etching process on a substrate. Wherein at least one of controlling the total flow rate of the gas having an etching property and the gas having a deposition property to a constant value before being supplied to the vacuum vessel after the flow rate is controlled by the plurality of first mass flow controllers. Characterized in that two second mass flow controllers are provided.

According to this configuration, by controlling the total flow rate of the gas supplied into the vacuum vessel to a constant value by the second mass flow controller, the transition time when the type of the gas supplied into the vacuum vessel is changed is obtained. Can easily keep the gas flow supplied to the vacuum container constant,
Since the fluctuation of the gas pressure in the vacuum vessel can be suppressed, the extinction of the gas plasma due to the fluctuation of the gas pressure can be prevented. Therefore, the disappearance and generation of plasma are not repeated,
Roughness does not occur on the etched side wall, and a high aspect ratio groove or hole having a smooth side wall can be formed.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a substrate processing apparatus according to an embodiment of the present invention.
An etching apparatus used for time-modulated etching is shown as an example. In FIG. 1, reference numeral 17 denotes a mass flow controller for controlling a gas flow rate, and reference numeral 27 denotes a valve. The other components that are the same as those in FIG. When using this etching apparatus, all the valves 21 to 27 are open.

In the present embodiment, as is apparent from comparison with FIG.
Is added after the pipes coming out of the mass flow controllers 13a and 13b merge.
The mass flow controller 17 controls the total flow rate of the gas supplied into the vacuum vessel 1 to a constant value. Other configurations are the same as those of the conventional etching apparatus.

FIG. 2 is a time chart showing the flow rate of each gas, the flow rate of the gas flowing into the vacuum vessel 1, and the pressure inside the vacuum vessel 1 by time-modulated etching in this embodiment.
First, in step 1, a gas A (etching gas) is supplied into the vacuum chamber 1 by controlling the mass flow controller 13 a and the mass flow controller 17 as an etching mode process mainly including etching. At this time, the mass flow controller 13b is closed, and the gas B (deposition gas) is not supplied into the vacuum vessel 1.

Next, as a transition time step at which the etching mode step is completed, the mass flow controller 13a is controlled to start closing from 0.5 to 1 second before completely closing the mass flow controller 13a. At about the same time, the mass flow controller 13b is controlled to start supplying the gas B. At this time, the mixed gas of the gas A and the gas B flows simultaneously through the mass flow controller 17, where the total flow rate is controlled. At the transition time to switch gas,
The total flow rate of the mixed gas of the gas A and the gas B is set to be larger than the set flow rate of the mass flow controller 17 before the mass flow controller 17, and the total flow rate of the mixed gas supplied into the vacuum vessel 1 is the mass flow rate. It is controlled by the controller 17 and becomes constant.

The work of setting the total gas flow rate before the mass flow controller 17 at the transition time to be larger than the set flow rate of the mass flow controller 17 is also necessary in the present embodiment, but this operation requires the mass flow controllers 13a and 13b. The timing of starting closing (timing of stopping gas supply) and the timing of starting opening (timing of supplying gas) can be easily achieved by appropriately adjusting the pressure of the vacuum vessel 1 while monitoring the pressure. This is because, as long as the total flow rate of the gas A and the gas B enters a region where the flow rate is larger than the flow rate set by the mass flow controller 17, the flow rate is finally controlled to be constant by the mass flow controller 17 thereafter.

Next, as a deposition mode process in step 2 after the transition, the mass flow controller 13a is closed to set the flow rate of the gas A to 0 so that the etching gas does not flow. At this time, the flow rate of the gas B is controlled by the mass flow controller 13b and the mass flow controller 17. The transition time at the end of the deposition mode process is the same as the transition time at the end of the etching mode, and the mass flow controller 13b is completely closed.
The gas A is started to be supplied by controlling the mass flow controller 13a 5 to 1 second before, and the mixed gas of the gas A and the gas B is caused to flow at the same time, and the total flow is controlled by the mass flow controller 17. Time-modulated etching is performed by repeating the above steps.

According to this method, by controlling the total flow rate of the gas supplied to the vacuum vessel 1 to a constant value, the vacuum vessel 1 can be switched even when the type of gas supplied to the vacuum vessel 1 is switched. Since the flow rate of the gas supplied into the chamber can be easily kept constant and the fluctuation of the gas pressure in the vacuum vessel 1 can be suppressed, the extinction of the gas plasma due to the fluctuation of the gas pressure can be prevented. Therefore, the extinction and generation of plasma are not repeated, and a groove or a hole having a high aspect ratio can be formed without roughening the etching side wall.

As described above, according to the present embodiment, since the flow rate of the gas supplied into the vacuum vessel 1 can be accurately controlled by the mass flow controller 17, the gas is supplied to the vacuum vessel 1 even at the gas transition time. The gas flow rate does not change and can be easily kept constant.
The gas pressure in the chamber can also be kept constant at all times. Accordingly, since the gas plasma does not disappear, the disappearance and generation of the plasma are not repeated, and the etching side wall is not roughened, so that a high aspect ratio groove or hole having a smooth side wall can be formed.

In this embodiment, the flow rate of the gas B is set to 0 at the time of the etching mode process. However, it is sufficient that the etching is performed without setting the flow rate of the gas B completely to zero. Gas A during deposition mode process
Although the flow rate of the gas A is set to 0, it is sufficient if the condition that the deposition occurs does not occur even if the flow rate of the gas A is not completely set to 0.

The present invention can be applied to any apparatus other than the etching apparatus, such as a sputtering apparatus or a CVD apparatus that generates a gas plasma inside a vacuum vessel and performs a predetermined process on the substrate.

[0029]

As described above, according to the present invention, by controlling the total flow rate of the gas supplied into the vacuum vessel to a constant value, the transition time when the type of the gas supplied into the vacuum vessel is changed is obtained. Also, the flow rate of the gas supplied into the vacuum vessel can be easily kept constant, and the fluctuation of the gas pressure in the vacuum vessel can be suppressed, so that the extinction of the gas plasma due to the fluctuation of the gas pressure can be prevented. Therefore, the disappearance and generation of plasma are not repeated, and the etching side wall is not roughened, and a groove or a hole having a smooth side wall and a high aspect ratio can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an etching apparatus that performs time-modulated etching, which is a substrate processing apparatus according to an embodiment of the present invention.

FIG. 2 is a time chart showing a flow rate of each gas, a flow rate of a gas flowing into a vacuum vessel, and a pressure inside the vacuum vessel by time-modulated etching in the embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of an etching apparatus that performs time-modulated etching, which is a conventional substrate processing apparatus.

FIG. 4 is a sectional view of an etching shape according to a conventional example.

FIG. 5 is a time chart of the flow rate of each gas by time modulation etching.

FIG. 6 is a time chart showing a flow rate of each gas, a flow rate of a gas flowing into a vacuum vessel, and a pressure inside a vacuum vessel by time-modulated etching when a transition time using a conventional etching apparatus is not optimal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum container 2 High frequency power supply for plasma generation 3 Matching controller 4 Inductive coupling coil 5 Dielectric plate 6 Substrate 7 Electrode 8 Matching controller 9 High frequency power supply for electrode application 10 Pressure controller 11 Turbo molecular pump 12a Etching gas cylinder 12b Deposition gas cylinder 13a Mass flow controller 13b Mass flow controller 14 Gas inlet 15 High frequency cable 16 High frequency cable for bias 17 Mass flow controller

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K057 DA04 DD09 DG07 DM40 5F004 AA02 BA20 BC03 BD04 CA02 DA00 EB01 FA08 5F045 DP03 EE04 EE13 EE19 EH11 HA03 HA13

Claims (4)

[Claims] A plurality of different gases are supplied to a vacuum vessel having a substrate installed therein while controlling the flow rate of each of the gases independently and time-dependently, and a gas plasma is generated inside the vacuum vessel. A substrate processing method for performing predetermined processing on the substrate by controlling a total flow rate of the plurality of different gases supplied into the vacuum vessel to a constant value. 2. A condition in which etching and deposition occur alternately and temporally by controlling the flow rates of a gas having an etching property and a gas having a deposition property in a vacuum vessel having a substrate installed therein. And etching the substrate by generating a gas plasma inside the vacuum vessel, wherein the etching gas supplied into the vacuum vessel and the deposition A substrate processing method comprising controlling a total flow rate with a gas having a property to a constant value. 3. A vacuum vessel in which a substrate is placed, and a plurality of first mass flow controllers for controlling flow rates of a plurality of different gases supplied to the vacuum vessel independently and time-dependently. A means for generating gas plasma inside the vacuum vessel to perform a predetermined process on the substrate, wherein the flow rate is controlled by the plurality of first mass flow controllers, A substrate processing apparatus comprising: at least one second mass flow controller for controlling a total flow rate of the plurality of different gases to a constant value before being supplied to the vacuum vessel. 4. A vacuum vessel in which a substrate is placed and a gas having an etching property and a gas having a deposition property supplied to the vacuum vessel are etched and deposited alternately at different flow rates over time. A plurality of first mass flow controllers for controlling to occur conditions;
Means for generating gas plasma inside the vacuum vessel to perform an etching process on the substrate, wherein the flow rate is controlled by the plurality of first mass flow controllers, and then the vacuum vessel Wherein at least one second mass flow controller for controlling a total flow rate of the gas having the etching property and the gas having the deposition property to a constant value before being supplied to the substrate processing apparatus.