JP5011148B2 - Semiconductor device manufacturing method, cleaning method, and substrate processing apparatus - Google Patents

Description

  The present invention relates to a method of manufacturing a semiconductor device and a substrate processing apparatus, and more particularly to cleaning of a substrate processing apparatus used in a high dielectric film forming process, which is one process of the manufacturing process of a semiconductor device.

  In general, in a substrate processing apparatus that forms a thin film on a substrate by a CVD method or an ALD method, in order to maintain the film thickness and its in-plane uniformity within a predetermined allowable range, the amount of particles generated is below a certain level. In order to suppress the cleaning, the cleaning of the processing chamber is performed every time the film thickness of the adhering material adhering to the portion other than the substrate such as the inner wall of the processing chamber reaches a certain cumulative thickness. There are a dry cleaning method using an etching gas and a wet cleaning method using an etchant for cleaning the processing chamber.

In the wet cleaning method, it is possible to replace a part to be cleaned with a part that has been cleaned in advance, and the time required for the replacement work is not a significant problem.
However, the process chamber is opened to the atmosphere for cleaning, and the parts that need cleaning such as the reaction vessel are removed from the machine for cleaning, so the heater cooling process, parts replacement process, heater heating process, temperature stabilization waiting process A series of steps such as a pre-coating step is required.

  Of these series of processes, the pre-coating process is designed to prevent film thickness fluctuations at the time of film formation before and after cleaning before starting the production of the product wafer and to prevent residual gas after cleaning from remaining. This is a necessary process for film formation under the same conditions as those for normal CVD film formation so that the processing chamber atmosphere is the same as for normal CVD film formation. Before starting the product wafer, the temperature of the substrate (wafer) should be the same before and after cleaning until not only the heater temperature but also the ambient temperature surrounding the wafer, such as the temperature of the processing chamber wall and shower head, are the same. Temperature stabilization time to stabilize is required. Accordingly, in order to clean the inside of the processing chamber by the wet cleaning method, it takes many times as long as the part replacement time, and the production capacity is significantly reduced.

  In other words, the down time during which the product cannot be started during the process chamber cleaning is not the length of the cleaning time itself, but the time for performing a series of processes such as heater temperature decrease + part replacement + heater temperature increase + temperature stabilization wait + precoat, This is many times longer than the cleaning time. Therefore, by reducing this time, the production capacity of the device is significantly improved.

On the other hand, in the dry cleaning method, an etching gas is introduced into a processing chamber, and a chemical reaction between the etching gas and the deposit causes the deposit to be detached from the deposition surface as a gaseous reactant (product). This is a method of cleaning by discharging gas as a gaseous substance, so there is no need to open the processing chamber to the atmosphere, and there are processes such as a heater temperature lowering process, a heater temperature increasing process, and a temperature stabilization waiting process due to the opening of the processing chamber to the atmosphere. Since it can be omitted, there is an advantage that the film formation can be resumed in a short time compared to the wet cleaning.
Therefore, it is preferable to use the dry cleaning method for cleaning the processing chamber rather than the wet cleaning method.

As an example of cleaning the processing chamber by the dry cleaning method, for example, when Si or W adheres, etching by thermal or remote plasma using ClF ₃ or NF ₃ as a cleaning gas is performed. ClF ₃ and NF ₃ are Si
It reacts with W and becomes a gaseous reaction product, for example, SiF ₄ or WF ₆ and is discharged outside. Since reaction products such as SiF ₄ and WF ₆ have the property of extremely high vapor pressure, the cleaning technology using ClF ₃ and NF ₃ is relatively easy to introduce and can be applied to mass production equipment. ing. As described above, it is a major premise that the etching gas is a gas that can generate a gaseous reaction product having a relatively high vapor pressure in order to desorb the deposit as a gaseous reaction product from the processing chamber. Become.

However, in the cleaning of a High-k film adhering to the inner surface of the processing chamber, for example, a high dielectric film containing Hf or Zr (HfO ₂ , HfSiO (hafnium silicate) or ZrO ₂ ), the reaction conditions described above are used. No substance (reaction product) with a high vapor pressure that can be satisfied has been found. Therefore, a promising etching gas has not yet been searched.

Accordingly, the present invention provides a method of manufacturing a semiconductor device and a substrate processing apparatus capable of cleaning a high dielectric film such as HfO ₂ , HfSiO, ZrO ₂ or the like adhering to the inner surface of a processing chamber with an etching gas. With the goal.

  According to one embodiment of the present invention, a step of carrying a substrate into a processing chamber, a step of forming a high dielectric film on the substrate in the processing chamber, and a step of carrying out the substrate after film formation from the processing chamber. Introducing a gas containing chlorine and a gas containing oxygen into the processing chamber or introducing a gas containing chlorine and oxygen to clean the processing chamber; and introducing a gas containing oxygen into the processing chamber And a step of removing a substance remaining in the processing chamber after the cleaning.

  According to another aspect of the present invention, a processing chamber for processing a substrate, a film forming gas introduction pipe for introducing a film forming gas for forming a high dielectric film into the processing chamber, and chlorine in the processing chamber. A gas introduction pipe for introducing a gas containing oxygen, a gas containing oxygen or a gas containing chlorine and oxygen, an exhaust pipe for exhausting the processing chamber, and a gas containing chlorine and a gas containing oxygen into the processing chamber. Alternatively, a gas containing chlorine and oxygen is introduced to clean the inside of the processing chamber, and then a gas containing oxygen is introduced into the processing chamber to control removal of substances remaining in the processing chamber after the cleaning. A substrate processing apparatus having a controller.

According to the present invention, it is possible to clean a high dielectric film such as HfO ₂ , HfSiO, ZrO ₂ or the like with an etching gas and to prevent generation of a solid product that causes contamination. The effect is demonstrated.

Hereinafter, an example of the substrate processing apparatus according to the present invention will be described with reference to FIG.
In this embodiment, a high dielectric constant film (High-k film) such as HfO ₂ , HfSiO, ZrO ₂ or the like is formed by CVD, more specifically, MOCVD (Metal Organic Chemical Deposition) or ALD. The case will be described.

FIG. 1 is a schematic view showing an example of a cold-wall type single-wafer substrate processing apparatus which is a substrate processing apparatus according to the present embodiment.
First, the configuration of the substrate processing apparatus will be described.
As shown in FIG. 1, a substrate loading / unloading port 60 for loading / unloading the substrate 30 is provided on the side wall of the processing chamber 4 for processing the substrate 30 such as a silicon wafer, and is opened and closed by a gate valve 46. The processing chamber 4 is provided with a susceptor 42 as a substrate support plate for supporting the substrate 30, and the susceptor 42 is supported by a support base 42a. A heater 43 for heating the substrate 30 is provided below the susceptor 42 inside the support base 42a.
A shower head 47 is provided above the processing chamber 4 so as to face the susceptor 42 and in parallel with the susceptor 42. In the shower plate 47a of the shower head 47, a large number, for example, several hundred to several tens of thousands of holes 48 as gas jets are arranged uniformly in the plane of the shower plate 47a.
Each hole 48 is narrowed to a very small conductance, and can supply a source gas and an etching gas for cleaning, which will be described later, onto the substrate 30 at a substantially uniform flow rate and flow rate.
A ring-shaped plate 49 is provided on the susceptor 42 as a rectifying plate for adjusting the flow of gas supplied from the shower head 47. The plate 49 is provided concentrically with the substrate 30.
The gas supplied from the holes 48 of the shower head 47 toward the substrate 30 collides with the substrate 30 and then flows outward in the radial direction of the substrate 30, and on the plate 49 and the side walls of the plate 49 and the processing container 202. The air is exhausted from the exhaust port 61 to the exhaust pipe 14 through (inner wall).
In addition, when there is a place where it is not desired to form a film on the substrate 30 such as the outer periphery of the substrate 30, the inner diameter of the plate 49 may be made smaller than the outer shape of the substrate 30 to cover the outer periphery of the substrate 30. . In this case, in order to enable the transfer of the substrate 30, the plate 49 may be fixed at a substrate processing position in the processing chamber 4, or a mechanism for moving the plate 49 up and down may be provided.

In the processing chamber 4, an Hf source gas supply pipe 17 a that supplies a gas obtained by vaporizing an Hf source as a first source containing a metal atom, for example, a hafnium atom, and a gas obtained by evaporating an Si source as a second source containing a silicon atom. Si source gas supply pipe 17b to be supplied, an inert gas supply pipe 12 for supplying an inert gas such as N ₂ and Ar, and an oxygen gas for supplying an oxidizing agent such as oxygen (oxidized gas) activated by the remote plasma unit 20 A supply pipe 16 is connected.

  Vent pipes 11a and 11b are connected to the Hf source gas supply pipe 17a and the Si source gas supply pipe 17b, respectively. The vaporizers 3a and 3b for vaporizing the Hf raw material and the Si raw material are connected to the Hf raw material gas supply pipe 17a and the Si raw material gas supply pipe 17b, respectively. These vaporizers 3a and 3b include Hf liquid source supply pipe 13a and Si liquid source via liquid flow rate control devices (liquid flow rate control means) 18a and 18b for adjusting the liquid flow rates of the Hf source and Si source, respectively. The Hf liquid source container 1 and the Si liquid source container 2 are connected by the supply pipe 13b.

  The Hf liquid raw material container 1 and the Si liquid raw material container 2 are pumped to push the respective raw materials in the Hf liquid raw material container 1 and the Si liquid raw material container 2 to the Hf liquid raw material supply pipe 13a and the Si liquid raw material supply pipe 13b. Pressure gas supply pipes 15a and 15b for supplying gas are connected to each other.

In such a configuration, when a pressurized gas such as N ₂ is supplied to the Hf liquid raw material container 1 and the Si liquid raw material container 2, each liquid raw material is pushed out to the liquid raw material supply pipes 13a and 13b, and the extruded liquid raw material is The gas is vaporized by the vaporizers 3a and 3b and supplied to the processing chamber 4 as a raw material gas via the raw material gas supply pipes 17a and 17b. The oxidizing gas (reformed gas) can be supplied to the processing chamber 4 after being activated via the remote plasma unit 20.
For example, argon (Ar) gas is used as the plasma ignition gas for generating plasma in the remote plasma unit 20.

  Further, an exhaust port 61 is provided in the lower side wall of the processing container 202, and the exhaust pipe 14 is connected to the exhaust port 61. In the exhaust pipe 14, from the upstream side toward the downstream side, a vacuum pump 5 as a decompression exhaust device (decompression exhaust means), a raw material recovery trap (not shown) for recovering the raw material, and a detoxification device (not shown). The pressure controller (APC: Auto Pressure Controller) 51 is provided on the upstream side of the vacuum pump 5 as a pressure control unit (pressure control means) for controlling the pressure in the processing chamber 4. In addition, a heating device is attached to various pipes in the figure as necessary in order to prevent adhesion of deposits.

Next, a configuration for cleaning with an etching gas will be described. A BCl ₃ -containing gas introduction pipe 52 for introducing BCl ₃ as a chlorine-containing gas and an O ₂ -containing gas as an oxygen-containing gas are introduced into the shower head 47. The O ₂ -containing gas introduction pipe 53 is connected, and the remote plasma unit 54 is interposed in the BCl ₃ -containing gas introduction pipe 52.
The BCl ₃ -containing gas introduction pipe 52 and the O ₂ -containing gas introduction pipe 53 are independent of each other and communicate with the inside of the processing chamber 4 through the holes 48 of the shower head 47.
The O ₂ -containing gas introduction pipe 53 is connected to an oxygen-containing gas supply source (not shown) via a gas flow rate control device (gas flow rate controller (gas mass flow controller)) 56 for adjusting the flow rate, and a BCl ₃ -containing gas introduction pipe. 52 is connected to a BCl ₃ -containing gas supply source (not shown) via a gas flow rate control device (gas flow rate controller (gas mass flow controller)) 55 for controlling the flow rate.
The remote plasma unit 54 may be provided in the BCl ₃ -containing gas introduction pipe 52 as shown in FIG. 2A, or the O ₂ -containing gas introduction pipe 53 as shown in FIG. As shown in FIG. 2C, it may be provided in both the BCl ₃ -containing gas introduction pipe 52 and the O ₂ -containing gas introduction pipe 53. That is, the remote plasma unit 54 may be interposed in at least one of the BCl ₃ -containing gas introduction pipe 52 and the O ₂ -containing gas introduction pipe 53. Further, as shown in FIG. 2 (d), a remote plasma unit 54 may be provided in the BCl ₃ -containing gas introduction pipe 52 and an ozonizer 57 may be provided in the O ₂ -containing gas introduction pipe 53. Note that as in FIG. 2 (b), the case of providing the remote plasma unit 54 to the O ₂ containing gas introduction pipe 53, O ₂ containing gas introduction pipe 53 for cleaning, a remote plasma unit 54, the oxygen for film formation The gas supply pipe 16 and the remote plasma unit 20 can be used in common (the oxygen gas supply pipe 16 and the remote plasma unit 20 become unnecessary), which is preferable.

  The controller 50 which is a control device includes liquid flow rate control devices 18a and 18b, gas flow rate control devices 55 and 56, vaporizers 3a and 3b, a remote plasma unit 20, a remote plasma unit 54, an ozonizer 57, a vacuum pump 5, and a pressure controller 51. The operation of each part constituting the single wafer CVD apparatus such as the heater 43 for heating the substrate 30 is controlled.

Next, as a process of manufacturing a semiconductor device, a method of forming, for example, an HfSiO film (hafnium silicate film) as a high dielectric film on the substrate 30 using the substrate processing apparatus, and cleaning the substrate processing apparatus How to do will be described. First, the substrate 30 is carried into the process chamber 4 from a transfer chamber (not shown) adjacent to the process chamber 4 by the substrate transfer apparatus.
Next, the substrate 30 is heated by the heater 43 to raise the temperature of the substrate 30 to the substrate processing temperature, and the pressure in the processing chamber 4 is held at a predetermined film forming pressure by the pressure controller 51.
Thereafter, a film forming step by the MOCVD method or the ALD method is started.
In the film forming step, a source gas, that is, an Hf source gas obtained by vaporizing an organometallic liquid source as an Hf source, for example, Hf [OC (CH ₃ ) ₂ CH ₂ OCH ₃ ] ₄ (hereinafter abbreviated as Hf-MMP) and Activated by the remote plasma unit 20 and an Si source gas obtained by vaporizing an organometallic liquid source as a Si source, for example, Si [OC (CH ₃ ) ₂ CH ₂ OCH ₃ ] ₄ (hereinafter abbreviated as Si-MMP). Oxidizing gas such as oxygen is supplied alternately several times.
That is, the Hf source gas and the Si source gas, which are controlled to a predetermined flow rate by the liquid flow rate control devices 18a and 18b and vaporized by the vaporizers 3a and 3b, are introduced into the shower head 47, and the flow rate is almost uniform from the shower head 47. -It is supplied onto the substrate 30 at a flow rate. The activated oxygen is supplied from the oxygen gas supply pipe 16.
At this time, since the substrate 30 placed on the susceptor 42 is heated to a predetermined temperature, that is, a film formation temperature, by the heater 43, an HfSiO film is formed on the substrate 30 with a desired film thickness.
Note that a purge with N ₂ as an inert gas (hereinafter simply referred to as N ₂ purge) is performed between the supply of the source gas (Hf source gas, Si source gas) and the supply of the oxidizing gas. N ₂ is supplied from the inert gas supply pipe 12.
As described above, in the film forming step by the MOCVD method or the ALD method, film forming is performed with a unit of one unit (one cycle) of Hf source gas and Si source gas supply → N ₂ purge → oxidation gas supply → N ₂ purge. The process is repeated an arbitrary number of times to form an HfSiO film having a desired film thickness.
In this case, the arbitrary number of times is the number of times the desired film thickness is divided by the film thickness obtained in one unit procedure.
In the film forming step, the Hf source gas and the Si source gas may be supplied simultaneously, or may be supplied intermittently to the substrate 30. That is, the procedure of Hf source gas supply → N ₂ purge → Si source gas supply → N ₂ purge → oxidation gas supply → N ₂ purge → is made one cycle, and this cycle may be repeated a plurality of times. .
Thereafter, the substrate 30 after the HfSiO film having a desired thickness is formed is unloaded from the processing chamber 4 to the transfer chamber by the substrate transfer device.

In addition, as a processing condition when processing the substrate 30 by the CVD method, for example, when forming an HfSiO film, a processing temperature: 350 to 450 ° C., a processing pressure: 50 to 400 Pa, a first raw material (Hf-MMP) ) Supply flow rate: 0.01 to 0.2 g / min, second raw material (Si-MMP) supply flow rate: 0.01 to 0.2 g / min, oxidizing gas (O ₂ ) supply flow rate: 100 to 3000 sccm The
The processing conditions for processing the substrate 30 by the ALD method include, for example, when forming an HfSiO film, processing temperature: 200 to 300 ° C., processing pressure: 50 to 400 Pa, first raw material (Hf-MMP) Supply flow rate: 0.01 to 0.2 g / min, second raw material (Si-MMP) supply flow rate: 0.01 to 0.2 g / min, oxidizing gas (O ₂ ) supply flow rate: 100 to 3000 sccm .

Such a film forming process is continuously or intermittently repeated, and HfO ₂ , HfSiO, ZrO ₂ adhering to the surface of the components in the processing chamber 4 such as the inner wall of the processing chamber 4, the surface of the susceptor 42, the plate 49, and the heater 43. When the accumulated film thickness of the high dielectric film (High-k film) such as the above becomes a predetermined thickness or more, the film thickness uniformity and the particles exceed the allowable range. For this reason, every time the film thickness reaches the predetermined film thickness, the inside of the processing chamber 4 is cleaned with the etching gas.

Hereinafter, a cleaning method using an etching gas for a high dielectric film such as HfO ₂ , HfSiO, ZrO ₂ or the like attached in the processing chamber of the substrate processing apparatus will be described.
_First, HfO 2, HfSiO, for identifying an etching gas can be used for the dry etching of the high dielectric film such as ZrO _2, gas to Cl 2, Cl ₂ was added _{O 2,} the _{O 2} to BCl 3, BCl ₃ Each of the added gases was introduced into an ECR plasma discharge atmosphere, and a test was conducted as to whether or not etching was possible.
A substrate processing apparatus having an ECR plasma generation source was used as the test apparatus, and a substrate on which a HfO ₂ or HfSiO film having a known film thickness was formed in advance was used as the test material.
The etching rate was determined from the difference in film thickness before and after etching. As a result, the following was found.
(1) The high dielectric film is not etched with Cl ₂ alone.
(2) Even when O ₂ is added to Cl ₂ , the high dielectric film is not etched.
(3) The high dielectric film is etched only when O ₂ is added to BCl ₃ .
(4) The etching rate of the high dielectric film is small only with BCl ₃ .
(5) A product having a relatively high vapor pressure such as HfClx (x = 1 to 3) or ZrCly (y = 1 to 3) by reacting with Cl atoms or radicals according to the above (1) to (4). In general, sub-chloride has higher vapor pressure than a stoichiometrically stable substance such as HfCl ₄ and ZrCl ₄ ), so that it is not possible to etch a high dielectric film. Etching does not proceed unless the reducing action of B (boron) is applied.
(6) When the amount of O ₂ added to BCl ₃ was changed between 0 and 100%, the etching rate was changed, and the amount of O ₂ added was maximized in the range of 10 to 30%. The result varies depending on the film quality of the high dielectric film. This is presumably because C (carbon) is contained in the high dielectric film, and etching is promoted when C reacts with O radicals generated by ECR plasma. For this reason, it is considered that the optimum value of the O ₂ addition amount varies depending on the C content.
(7) The etching rate also changes depending on the pressure of BCl ₃ + O ₂ gas, and the optimum value of the O ₂ addition amount changes. If the pressure in the processing chamber is increased too much, B alone or radicals containing B generated in the plasma act on the etching of the high dielectric film, but rather react with O or O ₂ to react with B ₂ O ₃ (solid). The reaction that produces is preferred. For this reason, it is important to perform the etching with a well-balanced pressure so that B ₂ O ₃ is not generated even if the reducing action of B moderately affects the etching of the high dielectric.

Thus, in order to clean a high dielectric film such as HfO ₂ , HfSiO, ZrO ₂ or the like with an etching gas, BCl ₃ gas or O ₂ gas supplied to the processing chamber as an etching gas is used as an ECR plasma generation source or in parallel. It is envisaged that a plasma generation source using a flat-plate electrode is used to generate plasma in the processing chamber, or a method of introducing the plasma into the processing chamber after converting to plasma.
However, ECR plasma generation sources and plasma generation sources using parallel plate electrodes are not directly related to CVD film formation and ALD film formation, and are excessive for installation in a substrate processing apparatus only for cleaning. It becomes equipment.
For this reason, in this embodiment, a remote plasma unit 54 using microwaves, RF, or the like is used, and the BCl ₃ -containing gas or O ₂ gas is activated by the remote plasma unit 54 and introduced into the processing chamber 4. This method is extremely simple and has great advantages in apparatus operation.

When cleaning is performed by supplying a BCl ₃ -containing gas and an O ₂ -containing gas to the processing chamber 4, a mixed gas in which BCl ₃ and O ₂ are mixed at an appropriate ratio is supplied to the remote plasma unit 54 and supplied after being converted into plasma. Before supplying the method and the processing chamber 4, at least one of the BCl ₃ -containing gas and the O ₂ -containing gas is converted into plasma by the remote plasma unit 54 in advance and supplied to the processing chamber 4 separately. There is a way to merge.
In the former method, a mixed gas is supplied to the remote plasma unit 54 and discharged in the remote plasma unit 54. At this time, B ₂ O ₃ solids are generated, and the generated B ₂ O ₃ solids are processed into the processing chamber 4. May be supplied inside.
In this regard, as in the latter method, before supplying to the processing chamber 4, at least one of the BCl ₃ -containing gas and the O ₂ -containing gas is plasma-excited using microwaves or RF, respectively, When supplied to the processing chamber 4 through a pipe, a high dielectric film such as HfO ₂ , HfSiO, ZrO ₂ or the like can be etched without generating such a B ₂ O ₃ solid.
This is because if one of BCl ₃ and O ₂ is activated by plasma, the energy transport between radicals and molecules will eventually cause decomposition and activation of both gases.
Therefore, in the present embodiment, at least one of the BCl ₃ -containing gas and the O ₂ -containing gas is plasma-excited and activated using remote plasma and supplied to the processing chamber 4 separately.

FIG. 2 is a schematic view showing a pattern example of a cleaning gas supply method for realizing such a method. In FIG. 2, 4 is a processing chamber of a substrate processing apparatus, 52 is a BCl ₃ -containing gas supply pipe, and 53 is O _2. The contained gas supply pipe 54 is a remote plasma unit for activation.

In the example shown in FIG. 2A, in the substrate processing apparatus, a BCl ₃ -containing gas introduction pipe 52 and an O ₂ -containing gas introduction pipe 53 are connected to the processing chamber 4, and only the BCl ₃ -containing gas introduction pipe 52 is remote. A plasma unit 54 is interposed.
When cleaning the high dielectric film, plasma-ized BCl ₃ -containing gas and O ₂ -containing gas are separately introduced into the processing chamber 4 from the BCl ₃ -containing gas introduction pipe 52 and the O ₂ -containing gas introduction pipe 53, respectively. First merge in the processing chamber 4.

In the example shown in FIG. 2B, a BCl ₃ -containing gas introduction pipe 52 and an O ₂ -containing gas introduction pipe 53 are connected to the processing chamber 4, and only the O ₂ -containing gas introduction pipe 53 is connected via a remote plasma unit 54. Has been established.
When cleaning the high dielectric film, the BCl ₃ -containing gas and O radicals activated by the remote plasma unit 54 are separately transferred from the BCl ₃ -containing gas introduction pipe 52 and the O ₂ -containing gas introduction pipe 53 to the processing chamber 4. It is introduced and merged in the processing chamber 4.

In the example shown in FIG. 2C, a BCl ₃ -containing gas introduction pipe 52 and an O ₂ -containing gas introduction pipe 53 are connected to the processing chamber 4, and the O ₂ -containing gas introduction pipe 53 and the BCl ₃ -containing gas introduction pipe are connected. A remote plasma unit 54 is provided on both of them.
When cleaning the high dielectric film, the BCl ₃ -containing gas and the O ₂ -containing gas are each converted into plasma by the remote plasma unit 54 and separately introduced into the processing chamber 4 and merged in the processing chamber 4.

In the example shown in FIG. 2D, a BCl ₃ -containing gas introduction pipe 52 and an O ₂ -containing gas introduction pipe 53 are connected to the processing chamber 4, and only the BCl ₃ -containing gas introduction pipe 52 is connected via a remote plasma unit 54. The ozonizer 57 is interposed only in the O ₂ -containing gas introduction pipe 53.
When cleaning the high dielectric film, the remote plasma unit 54 converts the BCl ₃ -containing gas into plasma, and a part of the O ₂ -containing gas is ozonized by the ozonizer 57 to form a mixed gas of O ₂ and O _3. 4 is introduced into the processing chamber 4.
O ₃ (ozone) generates O radicals by thermal decomposition on the surface of the substrate 30 at 350 ° C. or higher. In this case, the amount of O ₃ to be ozonized is preferably 1% or more of the whole.

FIG. 3 is a diagram comparing the gas supply system patterns shown in FIGS. 2A to 2D by etching rates. In the drawing, (a) to (d) correspond to the gas supply method patterns of (a) to (d) in FIG. 2, respectively. In FIG. 3, the vertical axis indicates the etching rate (arbitrary unit: au).
Normally, cleaning is performed by placing a dummy wafer on the heater so that members in the processing chamber (chamber) such as a susceptor do not generate metal contamination or particles due to cleaning damage. Here, the effectiveness of the cleaning is verified. The wafer with the HfO ₂ and HfSiO films whose film thicknesses are known in advance is placed on the heater, and the cleaning conditions are set to the same temperature (250 ° C.:=heater) as in the normal film formation. The etching rate was determined from the difference in film thickness before and after cleaning at a temperature of about 300 ° C., a pressure of 10 to 50 Pa, a BCl ₃ flow rate of about 300 sccm, and an O ₂ flow rate of about 700 sccm.
As a result, it has been found that a sufficient etching rate (etching rate) can be obtained and cleaning can be performed regardless of the size difference in any gas supply method pattern.
Although it is considered that a higher etching rate is better, it is difficult to determine which gas supply method is optimal because the device cost and the life of parts change depending on the use conditions.
As shown in FIG. 3, when the patterns (a) to (d) of the gas supply method of FIG. 2 are compared in terms of etching rate, both the BCl ₃ -containing gas and the O ₂ -containing gas are activated by plasma excitation and separately. 2 (FIG. 2 (c)) or a method in which BCl ₃ is converted into plasma and O ₂ is ozonized and supplied separately can provide a greater effect. However, in terms of cost reduction, FIG. As shown in (b) and (b), a method of converting one of BCl ₃ and O ₂ into plasma is preferable.

Figure 4 is in the gas supply system of FIG. 2 (a), BCl ₃ alone, the _{O 2} in the gas and Cl ₂ were added to BCl ₃ shows the etching rate of each etching gas of the gas with the addition of _{O 2.} In the figure, the vertical axis represents the etching rate (arbitrary unit: au). The target of etching is the above-described high dielectric film, and the cleaning conditions are the same as those in FIG.
As shown in FIG. 4, the etching rate is small with BCl ₃ alone, the etching rate becomes maximum when O ₂ is added to BCl ₃ , and the high dielectric film is etched when O ₂ is added to Cl _2. I understand that it is not done.

Figure 5 shows the gas supply system of FIG. 2 (a), _{O 2} dependency on BCl _3, i.e., the change in etch rate when the ratio of _{O 2} is changed for BCl _3. The object of etching is the above-described high dielectric film, and the cleaning conditions are the same as those in FIG.
In the figure, the horizontal axis represents the O ₂ concentration, and the vertical axis represents the etching rate (arbitrary unit: au).
As shown in FIG. 5, when the amount of O ₂ added to BCl ₃ is changed between 0 and 100%, the etching rate becomes maximum when the amount of O ₂ added is 30%, and decreases when the amount exceeds 30%. The tendency to do is seen.
Therefore, when the high dielectric film is cleaned by remote plasma using BCl ₃ + O ₂ as a cleaning gas, the amount of O ₂ added is preferably about 30%.

FIG. 6 shows the pressure dependency when the etching gas is BCl ₃ + O ₂ and the pressure in the processing chamber is changed in the gas supply system of FIG. In the figure, the horizontal axis represents pressure, and the vertical axis represents the etching rate (arbitrary unit: au).
The object of etching is the above-described high dielectric film, and the cleaning conditions are the same as those in FIG.
As shown in FIG. 6, when the pressure in the processing chamber changes, the etching rate also changes. When the etching gas is BCl ₃ + O ₂ , the etching rate becomes maximum when the pressure in the processing chamber is 10 Pa, and decreases when the pressure exceeds 10 Pa.
Therefore, when cleaning the high dielectric film by remote plasma using BCl ₃ + O ₂ as an etching gas, the pressure is preferably about 10 Pa.

The method for cleaning high dielectric films such as HfO ₂ , HfSiO, and ZrO ₂ by dry etching has been described above. However, these methods are applicable to the structure of the reaction vessel of the substrate processing apparatus, the operation method of the substrate processing apparatus, and the like. Based on these, you may choose from these.
In the present embodiment, BCl ₃ is exemplified as an example of a gas containing chlorine, but ClF ₃ may be used instead of BCl ₃ . When ClF ₃ is used, the same action and effect as BCl ₃ can be obtained. In addition, chlorine-containing gas such as BCl ₃ -containing gas and ClF ₃ -containing gas, and oxygen-containing gas such as O ₂ -containing gas and O ₃ -containing gas, as shown in FIG. On the basis of this, dilution may be performed with a diluent gas made of an inert gas (including rare gases) such as Ar and He. Dilution with a dilution gas can improve the agitation of the gas in the processing chamber 4 and can also adjust the etching rate. In the present embodiment, the example of cleaning using a chlorine-containing gas and an oxygen-containing gas has been described.
Cleaning can also be performed using a gas containing chlorine and oxygen, such as COCl ₂ (phosgene). In this case, since oxygen is contained in gas molecules, cleaning is performed without adding an oxygen-containing gas. Can do. That is, if the gas contains chlorine and oxygen such as COCl ₂ , the gas alone can be used for cleaning.

Next, a cleaning method in the manufacturing process of the semiconductor device will be specifically described.
First, in order to prevent metal contamination and particles from being generated due to cleaning damage of components in the reaction vessel such as the susceptor 42 after the substrate 30 on which a high dielectric film having a desired film thickness is unloaded from the processing chamber 4. Then, a dummy wafer for protecting the susceptor is placed on the susceptor 42 (dummy wafer placing step).
Thereafter, the temperature and pressure in the processing chamber 4 are adjusted to predetermined temperatures and pressures (temperature / pressure adjustment step), and the process waits until the discharge of the remote plasma unit (RPU) 54 is stabilized (discharge stabilization step).

Temperature in the processing chamber 4, the temperature at which pressure is suitable for cleaning a stable pressure, the discharge of the remote plasma unit 54 is stabilized, e.g., as described in FIG. ₂ (b), O 2 by the remote plasma unit 54 The contained gas is converted into plasma, and the O ₂ containing gas and the BCl ₃ containing gas that have been made into plasma are introduced into the processing chamber 4 separately through the O ₂ containing gas introduction pipe 53 and the BCl ₃ containing gas introduction pipe 52, respectively, and exhausted. Exhaust from the tube 14.
Further, for example, as described with reference to FIG. 2D, the remote plasma unit 54 converts the BCl ₃ -containing gas into plasma, and a portion of the O ₂ -containing gas is ozonized by the ozonizer 57 to mix O ₂ and O ₃ . The gas is exhausted from the exhaust pipe 14 while being introduced into the processing chamber 4 as a gas.
As a result, the high dielectric film adhered in the processing chamber 4 is removed (etched), and the processing chamber 4 is cleaned (cleaning step).

After cleaning with the etching gas comprising BCl ₃ -containing gas and O ₂ -containing gas is completed, the Cl-containing product remaining in the processing chamber 4 is exhausted by introducing the oxygen-containing gas into the processing chamber 4. Remove.
In this case, O ₂ containing at least one or more percent of O ₃ produced by using the ozonizer 57 shown in the remote plasma unit 54 O ₂ was plasma utilizing or Figure 2 (d) shown in FIG. 2 (b) A mixed gas of O ₂ and O ₃ is introduced into the processing chamber 4 as a purge gas, reacted with the Cl-containing product remaining in the processing chamber 4, and the processing chamber 4 is purged to remove it. The purge gas is exhausted from the exhaust pipe 14 (Cl-containing product removal step).

Thereafter, pre-coating (pre-deposition (conditioning)) is performed under the same film formation conditions as those of normal CVD film formation or ALD film formation so as not to cause film thickness fluctuations during film formation before and after cleaning, and the atmosphere in the processing chamber 4 is changed. Recover to the same state as before cleaning (precoat process). When this process is completed, the film forming process for the unprocessed substrate 30 is resumed.
2A to 2C, the processing conditions for cleaning the inside of the processing chamber 4 are, for example, processing temperature: 200 to 500 ° C., processing pressure: 10 to 10. Examples are 1000 Pa, BCl ₃ flow rate: 10 to 1000 sccm, and O ₂ flow rate: 10 to 500 sccm.
Moreover, as processing conditions when removing the Cl-containing product in the processing chamber 4 after cleaning, that is, purging conditions, for example, processing temperature: 200 to 500 ° C., processing pressure: 10 to 1000 Pa,
O ₂ flow rate: 100 to 2,000 are exemplified.
In the gas supply method pattern shown in FIG. 2D, the processing conditions for cleaning the inside of the processing chamber 4 are, for example, processing temperature: 200 to 500 ° C., processing pressure: 10 to 1000 Pa, BCl ₃ The flow rate is 10 to 1000 sccm, the O ₂ flow rate is 10 to 500 sccm, the O ₃ flow rate is 1 to 100 sccm, and the O ₃ concentration is 1 to 20%.
In addition, as processing conditions when removing the Cl-containing product in the processing chamber 4 after cleaning, that is, as purge conditions, for example, processing temperature: 200 to 500 ° C., processing pressure: 10 to 1000 Pa, O ₂ flow rate: Examples are 100 to 2000 sccm, O ₃ flow rate: 10 to 500 sccm, and O ₃ concentration: 1 to 20%.

(Effect of embodiment)
The embodiment of the present invention has the following effects.
A high dielectric film such as HfO ₂ , HfSiO, or ZrO ₂ can be cleaned by etching without opening the processing chamber to the atmosphere as in conventional wet etching.
Further, the downtime required for cleaning the processing chamber can be significantly shortened while maintaining the film thickness and in-plane uniformity characteristics before and after cleaning. As a result, the production capacity of the apparatus is greatly improved, the operation rate of the apparatus is improved, and the productivity is improved.

Actually, the inside of the processing chamber 4 of the substrate processing apparatus that has been used for a long time is cleaned by the cleaning method according to the present embodiment, and then the properties of the substrate when the high dielectric film is formed on the substrate 30 are verified. .
At the time of cleaning, a dummy wafer for suppressing damage was placed on the susceptor 42 for protection.
FIG. 7 shows a cleaning recipe used for cleaning.
As in this cleaning recipe, first, the pressure in the processing chamber 4 is adjusted. Moreover, it waits until discharge of the remote plasma unit (RPU) 54 is stabilized. In this example, the waiting time is about 15 minutes.
When the standby time has elapsed, as described with reference to FIG. 2B, the O ₂ gas is converted into plasma by the remote plasma unit 54, and the plasma O ₂ gas is transferred from the O ₂ -containing gas introduction pipe 53 to the processing chamber 4. be introduced. At the same time, BCl ₃ gas is introduced into the processing chamber 4 from BCl ₃ containing a gas inlet tube 52.
The cleaning conditions were the same as the cleaning conditions exemplified in the above cleaning method.
The time required for cleaning is about 1 hour.
After cleaning, (mixed gas of _{O 2} and _{O 3} containing at least one percent or more of _{O 3)} mixed gas of _{O 3} and _{O 2} was ozonized by _{O 2} gas or ozonizer 57 into plasma by the remote plasma unit 54 Was introduced into the processing chamber 4 and the inside of the processing chamber 4 was purged to remove the Cl-containing product remaining in the processing chamber 4.
The purge conditions were the same as the purge conditions exemplified in the above cleaning method.
The purge time is about 45 minutes.
Thereafter, pre-coating was performed under normal film forming conditions, and the pre-coating was performed for about 1 hour. After the pre-coating, the substrate 30 was carried into the processing chamber 4 to form a HfO ₂ film. The total time required is about 3.5 hours.
After film formation, the substrate 30 is unloaded from the processing chamber 4, and the film thickness and in-plane film thickness uniformity of the substrate 30 are measured, and the film thickness and in-plane film thickness uniformity measured in the film formation before cleaning are compared. Both the film thickness before and after cleaning and the variation in in-plane film thickness uniformity were within ± 2%, and good results were obtained.

[Comparative Example 1]
In the same cleaning cycle as in the example, BCl ₃ and O ₂ were preliminarily mixed and activated through the remote plasma unit 54 and then introduced into the processing chamber 4. The cleaning was performed in the same manner as in the example except for the gas supply method. However, the high dielectric film in the processing chamber 4 is not etched at all, and conversely, a thin film that seems to be some reaction product is formed on the dummy wafer for protecting the susceptor.
Elemental analysis of the surface of this dummy wafer by Auger spectroscopy revealed that B ₂ O ₃ was generated and transported onto the dummy wafer.
Further, after that, when the remote plasma unit 54 was disassembled and the inside was confirmed, it was observed that white fine particles adhered to the inner wall of the discharge tube in the form of a thin film.
That is, as in the comparative example, when BCl ₃ and O ₂ were mixed from the beginning and discharged in the remote plasma unit 54, the reaction proceeded too much before reaching the processing chamber 4, and the vitality was activated. Radicals or the like are not transported to the processing chamber 4, and only B ₂ O ₃ solid formation, which is a side effect, proceeds and this B ₂ O ₃ is transported into the processing chamber 4. From this, it can be said that it is extremely important to introduce BCl ₃ and O ₂ shown in the present invention in different systems.

[Appendix]
Hereinafter, preferred embodiments according to the present embodiment will be additionally described.

According to one embodiment of the present invention, a step of carrying a substrate into a processing chamber, a step of forming a high dielectric film on the substrate in the processing chamber, and a step of carrying out the substrate after film formation from the processing chamber. Introducing a gas containing chlorine and a gas containing oxygen into the processing chamber or introducing a gas containing chlorine and oxygen to clean the processing chamber; and introducing a gas containing oxygen into the processing chamber And a step of removing a substance remaining in the processing chamber after the cleaning.
In this case, in the process of cleaning the processing chamber, it is preferable that a gas containing chlorine and a gas containing oxygen are introduced into the processing chamber through separate introduction pipes.

According to another aspect of the present invention, a processing chamber for processing a substrate, a film forming gas introduction pipe for introducing a film forming gas for forming a high dielectric film into the processing chamber, and chlorine in the processing chamber. A gas introduction pipe for introducing a gas containing oxygen, a gas containing oxygen or a gas containing chlorine and oxygen, an exhaust pipe for exhausting the processing chamber, and a gas containing chlorine and a gas containing oxygen into the processing chamber. Alternatively, a gas containing chlorine and oxygen is introduced to clean the inside of the processing chamber, and then a gas containing oxygen is introduced into the processing chamber to control removal of substances remaining in the processing chamber after the cleaning. A substrate processing apparatus having a controller.
In this case, the gas introduction pipe has a chlorine gas introduction pipe for introducing a gas containing chlorine and an oxygen-containing gas introduction pipe for introducing a gas containing oxygen, and the chlorine-containing gas introduction pipe and the oxygen-containing gas The introduction pipes are preferably provided separately from each other.

The gas containing chlorine is preferably a gas containing BCl ₃ or ClF ₃ .
The gas containing chlorine and oxygen is preferably COCl ₂ .
Further, it is preferable to activate at least one of the gas containing BCl ₃ or ClF ₃ and the gas containing oxygen before introducing the gas into the processing chamber.

  Furthermore, the gas containing chlorine is preferably composed of a mixed gas diluted with at least one of rare gases such as Ar and He.

  The oxygen-containing gas is preferably composed of oxygen alone or a mixed gas diluted with at least one of rare gases such as Ar and He.

The oxygen-containing gas is preferably composed in advance of a mixed gas of O ₂ and O ₃ containing 1% or more of O ₃ produced by an ozonizer.
Furthermore, it is preferable that the chlorine-containing gas is excited in advance using microwaves, RF, or the like before introducing the chlorine-containing gas into the processing chamber as a gas containing active radicals.

The gas containing oxygen is previously plasma-excited using microwaves, RF, or the like before being introduced into the processing chamber, and is converted into a gas containing active oxygen atoms, excited O ₂ , ozone, or the like. It is preferable to introduce it indoors.

  After cleaning the treatment chamber using a gas containing chlorine and a gas containing oxygen or a gas containing chlorine and oxygen, oxygen gas alone or a gas containing oxygen gas is introduced, and chlorine remaining in the treatment chamber after cleaning is contained. It is preferred to remove the product.

After cleaning the processing chamber using a gas containing chlorine and a gas containing oxygen or a gas containing chlorine and oxygen, before introducing the oxygen gas alone or the gas containing oxygen gas into the processing chamber, Plasma-excited using RF (radio frequency) or the like, introduced into the treatment chamber as a gas containing active oxygen atoms, excited O ₂ , ozone, etc., and chlorine-containing products remaining in the treatment chamber after cleaning Is preferably removed.

In addition, after cleaning the processing chamber using a gas containing chlorine and a gas containing oxygen or a gas containing chlorine and oxygen, a mixture of O ₂ and O ₃ containing 1% or more of O ₃ produced by an ozonizer in advance. Gas may be introduced to remove Cl-containing products remaining in the processing chamber after cleaning.

  The high dielectric film is a film containing Hf or Zr.

It is the schematic which shows an example of the cold wall type single wafer type substrate processing apparatus which is the substrate processing apparatus which concerns on this Embodiment. It is the schematic which shows the example of a pattern of the cleaning method which concerns on one embodiment of this invention. FIG. 3 is a diagram for comparing the patterns shown in FIGS. 2A to 2D with etch rates. In this Embodiment, it is a figure which shows the gas kind used for dry etching, and its etching rate. In a plasma atmosphere, the amount of O ₂ added to BCl ₃ was varied between 0 to 100%, is a diagram showing the examination results of investigation of the added amount of O ₂ to the etching rate. It is a relationship diagram of the etching rate and pressure of the etching gas used in one embodiment of the present invention. It is a figure which shows an example of the cleaning recipe which concerns on one embodiment of this invention and is used for dry etching.

Explanation of symbols

4 Processing chamber 5 Vacuum pump 12 Oxygen supply pipe 14 Exhaust pipe 16 Oxygen gas introduction pipe 17a Hf source gas supply pipe (film formation gas introduction pipe)
17b Si source gas supply pipe (deposition gas introduction pipe)
20 Remote plasma unit 30 Substrate 42 Susceptor 43 Heater 52 BCl ₃ containing gas introduction pipe (chlorine containing gas introduction pipe)
53 O ₂ -containing gas introduction pipe (oxygen-containing gas introduction pipe)
54 Remote plasma unit 61 Exhaust port 57 Ozonizer 60 Substrate loading / unloading port 202 Processing vessel

Claims (8)

Carrying a substrate into the processing chamber;
Forming a high dielectric film on the substrate in the processing chamber;
Unloading the substrate after film formation from the processing chamber;
Introducing a gas containing chlorine and a gas containing oxygen into the processing chamber or introducing a gas containing chlorine and oxygen to clean the processing chamber;
A step of removing a substance remaining in the processing chamber after the cleaning by introducing the O ₂ gas into the processing chamber alone or by introducing a gas containing O ₂ gas without plasma excitation ; ,
A method for manufacturing a semiconductor device, comprising: _{2. The method} of manufacturing a semiconductor device according to claim 1, wherein in the step of removing the substance remaining in the processing chamber, O ₂ gas alone or a gas containing O ₂ gas is plasma-excited and introduced into the processing chamber. Method. In the step of removing the substance remaining in the processing chamber, O ₂ gas alone or a gas containing O ₂ gas is plasma-excited to obtain a gas containing active oxygen atoms, excited O ₂ , or O ₃ , The semiconductor device manufacturing method according to claim 1, wherein the semiconductor device is introduced into the processing chamber. 4. The method of manufacturing a semiconductor device according to claim 1, wherein in the step of removing the substance remaining in the processing chamber, a mixed gas of O ₂ gas and O ₃ gas is introduced. 5. . 5. The gas according to claim 1, wherein the gas containing chlorine is a gas containing BCl ₃ gas or ClF ₃ gas, and the gas containing chlorine and oxygen is a gas containing COCl _2. The manufacturing method of the semiconductor device of description. 6. The gas containing chlorine is a gas containing BCl ₃ gas.
The method for manufacturing a semiconductor device according to any one of the above. Introducing a gas containing chlorine and a gas containing oxygen or introducing a gas containing chlorine and oxygen into the processing chamber after performing a process of forming a high dielectric film on the substrate in the processing chamber Cleaning the processing chamber;
A step of removing a substance remaining in the processing chamber after the cleaning by introducing the O ₂ gas into the processing chamber alone or by introducing a gas containing O ₂ gas without plasma excitation ; ,
A cleaning method comprising: A processing chamber for processing the substrate;
A film forming gas introduction pipe for introducing a film forming gas for forming a high dielectric film into the processing chamber;
A gas introduction pipe for introducing a gas containing chlorine and a gas containing oxygen or a gas containing chlorine and oxygen into the processing chamber;
An exhaust pipe for exhausting the processing chamber;
Introducing a gas containing chlorine and a gas containing oxygen into the processing chamber, or introducing a gas containing chlorine and oxygen to clean the processing chamber, and then using O ₂ gas alone in the processing chamber, or A controller that controls to remove a substance remaining in the processing chamber after the cleaning by introducing a gas containing O ₂ gas without plasma excitation or without plasma excitation ;
A substrate processing apparatus comprising:

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