JP2009027011A - Substrate treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the residue of an etching element which causes reduction of film thickness. <P>SOLUTION: The substrate treatment device is provided with a treatment chamber 201 for treating a wafer 200, an etching gas supply means, such as, a gas supply pipe 232b for supplying F<SB>2</SB>-etching gas to the treatment chamber 201, a hydrogen radical supply means for supplying hydrogen radicals to the treatment chamber 201, and a controller 280 for controlling the etching gas supply means and the hydrogen radial supply means. The controller 280 makes the etching gas supply means supply the F<SB>2</SB>-etching gas to the treatment chamber 201 and then makes the hydrogen radical supply means supply hydrogen radicals to the treatment chamber 201. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a substrate processing apparatus, and more particularly to a technique useful for smoothly processing a substrate after cleaning with an etching gas.

  In recent years, with high density and multi-layer wiring of semiconductor DRAM, film formation at low temperature is required, and furthermore, film formation method and apparatus operation with excellent surface flatness, recessed portion embedding property, step coverage property and less foreign matter. Is required. Concerning the control of foreign matter, conventionally, the reaction tube has been removed and wet etching (immersion cleaning) has been performed, but recently, the film attached to the inner wall of the reaction tube by gas cleaning has been removed without removing the reaction tube. The removal method is generally performed.

  Gas cleaning methods include a method of exciting an etching gas with plasma and a method of exciting an etching gas with heat. Etching by plasma is often used in a single wafer apparatus from the viewpoint of uniformity of plasma density and bias voltage control. On the other hand, etching by heat is often used in a vertical apparatus. In order to suppress peeling of the film from the inner wall of the reaction tube or a jig such as a boat, the etching process is performed every time a film having a certain thickness is formed.

When performing the etching process by heating, the film thickness of the film formed after the etching process may decrease with respect to the target film thickness (film thickness before etching). As an example, FIG. 1 shows the transition of film thickness after cleaning with F ₂ gas in a Si ₃ N ₄ film formed by mixing dichlorosilane (DCS) and ammonia (NH ₃ ). It can be seen that the film thickness of Si ₃ N ₄ decreases by about 3% with respect to the target film thickness immediately after cleaning with F ₂ gas. In order to recover the film thickness of the Si ₃ N ₄ film from the evaluation of FIG. 1, it is necessary to form the Si ₃ N ₄ film with a thickness of 300 nm or more.

It is known that the amount of decrease in the film thickness varies depending on the supply time and supply pressure of the F ₂ gas, and increases as the time increases or the pressure increases. A method conventionally used as a method for preventing the decrease in the film thickness is a method of forming a Si ₃ N ₄ film called “predeposition” as described above. However, if predeposition is performed several times in order to recover the film thickness of the Si ₃ N ₄ film, time loss occurs, and the substantial formation of the Si ₃ N ₄ film until the next etching with F ₂ gas is performed. There was a problem that the number of membranes was reduced.

  Therefore, a main object of the present invention is to provide a substrate processing apparatus capable of reducing the remaining etching elements that cause a decrease in film thickness.

According to the present invention,
A processing chamber for processing the substrate;
An etching gas supply means for supplying an etching gas of any one of a fluorine-based etching gas, a chlorine-based etching gas, or a mixed etching gas in which the fluorine-based etching gas and the chlorine-based etching gas are combined;
Hydrogen radical supply means for supplying hydrogen radicals to the processing chamber;
Control means for controlling the etching gas supply means and the hydrogen radical supply means;
With
There is provided a substrate processing apparatus, wherein the control unit causes the etching gas supply unit to supply the etching gas to the processing chamber, and then causes the hydrogen radical supply unit to supply the hydrogen radical to the processing chamber. The

  According to the present invention, since the hydrogen radical supply means is provided, and the control means supplies the etching radical to the processing chamber and then supplies the hydrogen radical to the processing chamber, fluorine or chlorine derived from the etching gas remaining in the processing chamber. Reacts with hydrogen radicals to form hydrogen fluoride or hydrogen chloride, which can be exhausted. Therefore, it is possible to suppress the etching elements that cause the film thickness from being reduced, such as fluorine and chlorine, which remain in the processing chamber, and to reduce the remaining etching elements in the processing chamber.

  Next, preferred embodiments of the present invention will be described with reference to the drawings.

[Etching principle]
First, let us consider the reason why the film thickness after etching decreases.
As an example, assuming that F ₂ is supplied into a processing chamber in which a Si ₃ N ₄ film is formed by a CVD (Chemical Vapor Deposition) method, the reaction is considered as follows.

(I) etching the _Si 3 _{N 4} according to the _{F 2 Si 3 N 4 + 6F} 2 → 3SiF 4 + 2N 2 ... (1)
(Ii) Adsorption of F atoms on quartz tube (reaction tube) (iii) Si ₃ N ₄ film formation 3SiH ₂ Cl ₂ + 4NH ₃ → Si ₃ N ₄ + 6HCl + 6H ₂ (2)

(Iv) Desorption of F atoms (radicals) into the processing chamber (v) Reaction of DCS and F atoms in the gas phase during Si ₃ N ₄ film formation SiH ₂ Cl ₂ + 4F ^* → SiF ₄ + 2HCl (3)
(Vi) Etching of Si ₃ N ₄ film with F atoms Si ₃ N ₄ + 12F ^* → 3SiF ₄ + 2N ₂ (4)

Here, steps (i) and (ii) represent etching by F ₂ and adsorption of F atoms. F atoms are adsorbed not only on the inner wall of the quartz tube (reaction tube) but also on relatively low-temperature parts such as a heat insulating plate and a seal cap part near the furnace port.

Steps (iv), (v), and (vi) are steps that cause a reduction in film thickness during the Si ₃ N ₄ film formation. The F atoms adsorbed in the reaction tube in (i) and (ii) are desorbed into the gas phase when the processing chamber is heated and evacuated to vacuum, and as shown in step (v), SiH ₂ Cl ₂ ( Or an intermediate product), which is a factor for substantially reducing the concentration of the raw material gas. Further, as shown in the step (vi), it is considered that the F atoms desorbed on the formed Si ₃ N ₄ film undergo an adsorption reaction and the etching proceeds, which causes a decrease in the thickness of the Si ₃ N ₄ film. It has become. Considering the countermeasures from the examination of these causes, it is considered that the F atoms adsorbed and desorbed should be reduced.

Therefore, a preferred embodiment of the present invention proposes a method for efficiently removing F atoms adsorbed on the surface of a quartz tube (reaction tube) or a metal member by etching using F ₂ gas. For example, the following three methods can be proposed as a method for removing F atoms.

The first method is a method of supplying H ₂ O into the processing chamber. Heat-excited water molecules (H ₂ O) are opened to generate HO ^* and H ^* .
H ₂ O → HO ^* + H ^* (5)
Active hydrogen radicals (H ^* ) react with F atoms desorbed in the gas phase to form HF and are exhausted.
H ^* + F ^* → HF (6)

The second method uses hydrogen radicals generated by plasma excitation of hydrogen or a hydrogen compound (such as NH ₃ ).
When using hydrogen plasma,
H ₂ → H ^* + H ^* (7)
When using NH ₃ plasma,
NH ₃ → NH ₂ ^* + H ^* (8)
Active hydrogen radicals (H ^* ) react with F atoms by the reaction shown by the formula (6) to form HF and are exhausted.

The third method is a method using thermal decomposition of NH ₃ .
NH ₃ is heated to generate hydrogen radicals (H ^* ) as shown in Formula (8). The generated active H ^* reacts with F atoms to form HF and is exhausted as shown in the formula (6).

FIG. 2 is a plot of the film thickness and the film thickness reduction rate for each batch in the case where the Si ₃ N ₄ film is formed after the F ₂ etching.
The film thickness of the Si ₃ N ₄ film is restored to the film thickness before etching by performing three batches of predeposition. In Run 1, the reduction rate was 3%, but in Run 2 and Run 3, 1.4% and 0.9%, the reduction rate decreased with each film formation, and in Run 4, the film thickness before etching was obtained. This is considered to be because the hydrogen radicals generated during the Si ₃ N ₄ film formation consumed and reduced F ^* adsorbed and desorbed in the processing chamber by the reaction of formula (6).

FIG. 3 shows the film thickness transition of the Si ₃ N ₄ film when the NH ₃ plasma treatment which is the second method is performed.
Even after the F ₂ etching is performed, the influence of F ^* can be eliminated by performing the NH ₃ plasma treatment, and the film thickness of the Si ₃ N ₄ film shows a constant value without decreasing.

  Next, the hydrogen radical supply process to a process chamber is demonstrated.

First, FIG. 4 shows steps of a conventional method using a predepot.
The pre-deposition is performed under the same film forming conditions as those for forming the Si ₃ N ₄ film. In order to eliminate the influence of F, it is necessary to form a Si ₃ N ₄ film having a thickness of 200 to 300 nm. This may be formed continuously or may be divided.

On the other hand, the first method for reducing the adsorbed F is a method of performing H ₂ O treatment after F ₂ etching. FIG. 5 shows the H ₂ O treatment process. H ₂ O is performed using a H ₂ O supply device using a bubbler or a Pt catalyst.

The second method for reducing F is a pretreatment with H ₂ plasma or NH ₃ plasma. FIG. 6 shows a pretreatment process using H ₂ plasma or NH ₃ plasma. In the plasma processing, H ₂ or NH ₃ is normally excited at a high frequency of 13.56 MHz, and the processing chamber is purged with N ₂ after the plasma processing for a certain time.

The third method for reducing F is NH ₃ pretreatment by heat excitation. FIG. 7 shows a pretreatment process by thermal decomposition of NH ₃ . Pyrolysis process of the NH ₃ is the same effect of what proportion of excited is small NH ₃ compared to the plasma treatment is obtained.

  Next, the substrate processing apparatus and the F atom removal method according to a preferred embodiment of the present invention will be described in more detail based on the matters described in [Etching Principle] above. In the following description, the configuration and method for carrying out the first method (see FIG. 5) in Example 1 will be exemplified, and in order to carry out the second method (see FIG. 6) in Example 2. The configuration and the method thereof are illustrated, and the configuration and the method for implementing the third method (see FIG. 7) in Example 3 are illustrated.

[Device configuration]
First, a substrate processing apparatus according to a preferred embodiment of the present invention will be described with reference to FIGS.

  As shown in FIGS. 8 and 9, the semiconductor device manufacturing apparatus 101 uses a cassette 110 as a wafer carrier containing a wafer 200 made of a material such as silicon. The semiconductor device manufacturing apparatus 101 includes a housing 111. Below the front wall 111a of the housing 111, a front maintenance port 103 is provided as an opening provided so as to allow maintenance. A front maintenance door 104 that can be opened and closed is built in the front maintenance port 103.

  A cassette loading / unloading port 112 is opened in the maintenance door 104 so as to communicate between the inside and outside of the casing 111, and the cassette loading / unloading port 112 is opened and closed by a front shutter 113.

  A cassette stage 114 is installed inside the casing 111 of the cassette loading / unloading port 112. The cassette 110 is carried into the cassette stage 114 or carried out from the cassette stage 114 by an in-factory transfer device (not shown).

  The cassette stage 114 is placed by the in-factory transfer device so that the wafer 200 maintains a vertical posture in the cassette 110 and the wafer loading / unloading port of the cassette 110 faces upward. The cassette stage 114 can operate so that the cassette 110 rotates 90 degrees clockwise and rearwardly in the rear of the casing 111, the wafer 200 in the cassette 110 is in a horizontal position, and the wafer loading / unloading port of the cassette 110 faces the rear of the casing 111. It is comprised so that.

  A cassette shelf 105 is installed at a substantially lower center in the front-rear direction in the casing 111. The cassette shelf 105 is configured to store a plurality of cassettes 110 across a plurality of stages and a plurality of rows. The cassette shelf 105 is provided with a transfer shelf 123 in which the cassette 110 to be transferred by the wafer transfer mechanism 125 is stored. A spare cassette shelf 107 is installed above the cassette stage 114 and is configured to store the spare cassette 110.

  A cassette carrying device 118 is installed between the cassette stage 114 and the cassette shelf 105. The cassette carrying device 118 includes a cassette elevator 118a that can move up and down while holding the cassette 110, and a cassette carrying mechanism 118b as a carrying mechanism. The cassette carrying device 118 carries the cassette 110 among the cassette stage 114, the cassette shelf 105, and the spare cassette shelf 107 by continuous operation of the cassette elevator 118a and the cassette carrying mechanism 118b.

  A wafer transfer mechanism 125 is installed behind the cassette shelf 105. The wafer transfer mechanism 125 includes a wafer transfer device 125a that can rotate or linearly move the wafer 200 in the horizontal direction, and a wafer transfer device elevator 125b that moves the wafer transfer device 125a up and down. Wafer transfer device elevator 125 b is installed at the right end of pressure-resistant housing 111. The wafer transfer mechanism 125 picks up the wafer 200 by the tweezer 125c of the wafer transfer device 125a and loads (charges) the wafer 200 into the boat 217 by continuous operation of the wafer transfer device 125a and the wafer transfer device elevator 125b. Or the boat 217 is detached (discharged).

  As shown in FIGS. 8 and 9, a processing furnace 202 is provided above the rear portion of the casing 111. The lower end portion of the processing furnace 202 is configured to be opened and closed by a furnace port shutter 147.

  Below the processing furnace 202, a boat elevator 115 for raising and lowering the boat 217 to the processing furnace 202 is installed. An arm 128 as a connecting tool is connected to the boat elevator 115, and a seal cap 219 as a lid is horizontally installed on the arm 128. The seal cap 219 supports the boat 217 vertically, and is configured so that the lower end portion of the processing furnace 202 can be closed.

  The boat 217 includes a plurality of holding members, and is configured to hold a plurality of (for example, about 50 to 150) wafers 200 horizontally with the centers thereof aligned in the vertical direction. Yes.

  As shown in FIGS. 8 and 9, a clean unit 134 a for supplying clean air that is a cleaned atmosphere is installed above the cassette shelf 105. The clean unit 134 a includes a supply fan and a dustproof filter, and is configured to distribute clean air inside the casing 111.

  A clean unit (not shown) for supplying clean air is also installed at the left end of the casing 111 on the opposite side of the wafer transfer device elevator 125b and the boat elevator 115 side. The clean unit is also composed of a supply fan and a dustproof filter, like the clean unit 134a. Clean air supplied from the clean unit circulates in the vicinity of the wafer transfer device 125a, the boat 217, and the like, and is then exhausted to the outside of the casing 111.

  Next, the operation of the semiconductor device manufacturing apparatus 101 will be described.

  As shown in FIGS. 8 and 9, the cassette loading / unloading port 112 is opened by the front shutter 113 before the cassette 110 is supplied to the cassette stage 114. Thereafter, the cassette 110 is loaded onto the cassette stage 114 from the cassette loading / unloading port 112. At this time, the wafer 200 in the cassette 110 is held in a vertical posture, and is placed so that the wafer loading / unloading port of the cassette 110 faces upward.

  Thereafter, the cassette 110 is rotated 90 ° clockwise by the cassette stage 114 so that the wafer 200 in the cassette 110 is in a horizontal posture and the wafer loading / unloading port of the cassette 110 faces the rear of the casing 111.

  Next, the cassette 110 is automatically transported and delivered by the cassette transport device 118 to the designated shelf position of the cassette shelf 105 or the spare cassette shelf 107, temporarily stored, and then stored in the cassette shelf 105 or the spare shelf. It is transferred from the cassette shelf 107 to the transfer shelf 123 by the cassette transfer device 118 or directly transferred to the transfer shelf 123.

  When the cassette 110 is transferred to the transfer shelf 123, the wafers 200 are picked up from the cassette 110 through the wafer loading / unloading port by the tweezer 125c of the wafer transfer device 125a, and loaded (charged) into the boat 217 at the rear of the transfer chamber 124. ) The wafer transfer device 125 a that has delivered the wafer 200 to the boat 217 returns to the cassette 110 and loads the next wafer 200 into the boat 217.

  When a predetermined number of wafers 200 are loaded into the boat 217, the lower end portion of the processing furnace 202 closed by the furnace port shutter 147 is opened by the furnace port shutter 147. Subsequently, the boat 217 holding the group of wafers 200 is loaded into the processing furnace 202 when the seal cap 219 is lifted by the boat elevator 115.

  After loading, arbitrary processing (see later) is performed on the wafer 200 in the processing furnace 202. After the processing, the cassette 110 and the wafer 200 are carried out of the casing 111 in the reverse procedure.

[Processing furnace configuration]
The processing furnace 202 used in the substrate processing apparatus described above will be described with reference to FIGS. In the present embodiment, a description will be given of F ₂ etching of a Si ₃ N ₄ film as an example.

Each gas of DCS, NH ₃ , H ₂ O, and F ₂ is introduced into the processing furnace according to the present embodiment. In particular, DCS and NH ₃ are introduced as processing gases during film formation, and F ₂ is introduced during etching. . Then, a H ₂ O process is performed as a process after the etching.

  As shown in FIG. 10, the processing furnace 202 is provided with a heater 207 which is a heating device. Inside the heater 207, a reaction tube 204 capable of accommodating a wafer 200, which is an example of a substrate, is provided. The reaction tube 204 is made of quartz. A manifold 203 made of, for example, stainless steel is provided below the reaction tube 204. Annular flanges are formed on the lower part of the reaction tube 204 and the upper part of the manifold 203, respectively.

  An O-ring 220 is provided between the flanges of the reaction tube 204 and the manifold 203 so that the space between the reaction tube 204 and the manifold 203 is hermetically sealed. A lower portion of the manifold 203 is airtightly closed by a seal cap 219 that is a lid through an O-ring 220. In the processing furnace 202, a processing chamber 201 for processing the wafer 200 is formed by at least the reaction tube 204, the manifold 203, and the seal cap 219.

  A boat 217 as a substrate holding member is erected on the seal cap 219 via a boat support base 208. The boat support 208 is a holding body that holds the boat 217. The boat 217 is disposed at the substantially central portion of the reaction tube 204 while being supported by the boat support 208 and is inserted into the processing chamber 201. A plurality of wafers 200 to be batch-processed are stacked on the boat 217 in multiple stages in the vertical direction in FIG. The wafer 200 accommodated in the processing chamber 201 is heated to a predetermined temperature by the heater 207.

  The boat 217 can be raised and lowered in the vertical direction in FIG. 10 by a boat elevator 115 (see FIG. 8), and can enter and exit (up and down) the reaction tube 204. Below the boat 217, a boat rotation mechanism 267 for rotating the boat 217 is provided to improve processing uniformity, and the boat 217 held on the boat support 208 is rotated by the boat rotation mechanism 267. It can be made to.

  In this embodiment, four gas supply pipes 232a, 232b, 232c, and 232d for supplying four kinds of gases are provided.

  The gas supply pipes 232a and 232b are provided with mass flow controllers 241a and 241b, which are flow rate control devices, and valves 242a and 242b, which are on-off valves, in order from the upstream. A carrier gas supply pipe 234a for supplying a carrier gas is connected to the gas supply pipes 232a and 232b. The carrier gas supply pipe 234a is provided with a mass flow controller 240a, which is a flow rate control device, and a valve 243a, which is an on-off valve, in order from upstream.

  The ends of the gas supply pipes 232a and 232b are connected to the nozzle 252. The nozzle 252 extends in an up-down direction in FIG. 10 in an arc-shaped space between the inner wall of the reaction tube 204 constituting the processing chamber 201 and the wafer 200. A plurality of gas supply holes 253 are formed on the side surface of the nozzle 252. The gas supply holes 253 have the same opening area, and are formed at the same opening pitch from the bottom to the top.

  The gas supply pipe 232c is provided with a mass flow controller 241c as a flow rate control device and a valve 242c as an on-off valve in order from the upstream. A carrier gas supply pipe 234b for supplying a carrier gas is connected to the gas supply pipe 232c. The carrier gas supply pipe 234b is provided with a mass flow controller 240b that is a flow rate control device and a valve 243b that is an on-off valve in order from the upstream.

  An end portion of the gas supply pipe 232 c is connected to the nozzle 255. The nozzle 255 extends in an up-down direction in FIG. 10 in an arc-shaped space between the inner wall of the reaction tube 204 constituting the processing chamber 201 and the wafer 200. A plurality of gas supply holes 256 are formed on the side surface of the nozzle 255. The gas supply holes 256 have the same opening area and are formed at the same opening pitch from the bottom to the top.

  The gas supply pipe 232d is provided with a mass flow controller 241d as a flow rate control device and a valve 242d as an on-off valve in order from the upstream. A carrier gas supply pipe 234c that supplies a carrier gas is connected to the gas supply pipe 232d. The carrier gas supply pipe 234c is provided with a mass flow controller 240c, which is a flow control device, and a valve 243c, which is an on-off valve, in order from the upstream.

  The end of the gas supply pipe 232d is connected to the nozzle 258. The nozzle 258 extends in an up-down direction in FIG. 10 in an arc-shaped space between the inner wall of the reaction tube 204 constituting the processing chamber 201 and the wafer 200. A plurality of gas supply holes 259 are formed on the side surface of the nozzle 258. The gas supply holes 259 have the same opening area and are formed at the same opening pitch from the bottom to the top.

In this embodiment, DCS flows into the gas supply pipe 232a, F ₂ into the gas supply pipe 232b, NH ₃ into the gas supply pipe 232c, and H ₂ O into the gas supply pipe 232d. Further, N ₂ flows into the gas supply pipes 234a, 234b, 234c.

  One end of a gas exhaust pipe 231 for exhausting gas is connected to the processing chamber 201. The other end of the gas exhaust pipe 231 is connected to a vacuum pump 246 so that the inside of the processing chamber 201 can be evacuated. The gas exhaust pipe 231 is provided with a valve 243e. The valve 243e is an on-off valve that can open and close the valve to evacuate / stop the evacuation of the processing chamber 201 and adjust the valve opening to adjust the pressure.

  Each member such as the mass flow controllers 241a to 241d, 240a to 240c, valves 242a to 242d, 243a to 243c, and 243e, the heater 207, the vacuum pump 246, the boat rotation mechanism 267, and the boat elevator 115 is a controller 280 that is a control unit. It is connected to the.

  The controller 280 adjusts the flow rate of the mass flow controllers 241a to 241d and 240a to 240c, opens and closes the valves 242a to 242d and 243a to 243c, opens and closes the valve 243e and adjusts the pressure, adjusts the temperature of the heater 207, and activates the vacuum pump 246. The stop, the boat rotation mechanism 267 rotation speed adjustment, the lifting operation of the boat elevator 115, and the like are controlled.

  Next, an example of a film forming process using the processing furnace 202 will be described. In this embodiment, an example using the CVD apparatus of FIGS. 10 and 11 will be described.

First, the F ₂ etching process will be described. In the F ₂ etching, the wafer 200 is not loaded into the boat 217 and only the boat 217 is carried into the processing chamber 202. After the boat 217 is carried into the processing chamber 201, processing of the following steps described later is sequentially performed.

(Step 1)
F ₂ gas is used at a concentration of 100% or a concentration diluted with N ₂ by about 20%. The valve 242b is opened, F ₂ gas is allowed to flow into the nozzle 252 from the gas supply pipe 232b, and is introduced into the processing chamber 201 from the gas supply hole 253 of the nozzle 252. When diluting and using F ₂ gas, the valve 243a is also opened, and N ₂ is caused to flow from the gas supply pipe 234a into the gas supply pipe 232b. In Step 1, the inside of the processing chamber 201 is evacuated in advance, and F ₂ gas is introduced into the processing chamber 201 with the valve 243e opened.

The valve 243e is opened and closed every time a certain time elapses (the valve 243e is repeatedly opened and closed every certain time), and the inside of the processing chamber 201 is etched with F ₂ gas. When the etching is completed, the valves 242b and 243a are closed to evacuate the inside of the processing chamber 201, and then the valve 243a is opened to purge the processing chamber 201 with N ₂ gas.

As an etching gas, an F-containing gas such as ammonium trifluoride (NF ₃ ) gas, hydrogen fluoride (HF) gas, chlorine trifluoride (ClF ₃ ) gas, or boron trichloride ( A Cl-containing gas such as BCl ₃ ) gas can also be used.

(Step 2)
In step 2, treatment with H ₂ O is performed to remove F ₂ remaining in the treatment chamber 201.
The valve 242d is opened, and H ₂ O gas is introduced into the nozzle 258 from the gas supply pipe 232d and introduced into the processing chamber 201 from the gas supply hole 259 of the nozzle 258. At this time, the H ₂ O gas is excited by receiving heat from the heater 207 to generate hydrogen radicals. When the H ₂ O gas is allowed to flow into the gas supply pipe 232d, a moisture generator using a bubbler or a Pt catalyst is used. In Step 2, the valve 243e is kept open, and the inside of the processing chamber 201 is evacuated by the vacuum pump 246.

(Step 3)
In step 3, a Si ₃ N ₄ film is formed on the wafer 200.
The wafers 200 are transferred to the boat 217 and the boat 217 is loaded into the processing chamber 201. Thereafter, DCS and NH ₃ gas are mixed and supplied from the gas supply pipes 232a and 232c to the processing chamber 201, and a CVD film is formed on the wafer 200.

Specifically, the valve 242a is opened to allow DCS to flow into the nozzle 252 from the gas supply pipe 232a, and is introduced into the processing chamber 201 from the gas supply hole 253 of the nozzle 252, and the valve 242c is opened to supply NH ₃ gas. It flows into the nozzle 255 from the tube 232 c and is introduced into the processing chamber 201 through the gas supply hole 256 of the nozzle 255. The supply amount of DCS is controlled by the mass flow controller 241a, and the supply amount of NH ₃ gas is controlled by the mass flow controller 241c. As a result, a Si ₃ N ₄ film is formed on the wafer 200.

By changing the type of processing gas (DCS or NH ₃ ), the wafer 200 has a Si-based film such as a SiO ₂ film or a Poly-Si film, or a high dielectric film such as a HfO ₂ film or a ZrO ₂ film. Can also be formed. In Steps 1 to 3, preferably, the heater 207 is controlled to set the temperature in the processing chamber 201 to 300 to 700 ° C. Further, in Steps 1 to 3, preferably the pressure in the processing chamber 201 is set to 1 to 10,000 Pa by controlling the valve 243e and the like.

(Step 4)
The process of step 3 is repeated a plurality of times to form a Si ₃ N ₄ film having a predetermined thickness, and when the maintenance time comes, the etching process of step 1 is performed again.

According to the above embodiment, after supplying the _{F 2} gas into the processing chamber 201 at step 1, the _{H 2} O process in Step 2, the the _{H 2} O gas by introducing _{H 2} O gas into the processing chamber 201 Is excited by the heat of the heater 207 to generate hydrogen radicals, so that F ₂ (F ^* ) remaining in the processing chamber 201 reacts with the hydrogen radicals and is exhausted from the gas exhaust pipe 231 as HF. Therefore, it is possible to reduce the etching element F, which causes a decrease in the thickness of the Si ₃ N ₄ film, from remaining in the processing chamber 201, and thus to recover the thickness of the Si ₃ N ₄ film. Conventional pre-depot processing is also unnecessary.

  The second embodiment is different from the configuration and processing contents according to the first embodiment mainly in the following points, and is otherwise the same as the first embodiment.

The processing furnace 202 according to the second embodiment is used for ALD film formation. The processing chamber 201 _DCS, introduced each gas NH 3, _{F 2,} in particular DCS as the process gas during deposition, the NH _3, at the time of etching _{F 2} is introduced. Then, NH ₃ plasma treatment is performed as a treatment after etching.

  As shown in FIGS. 12 and 13, in this embodiment, three gas supply pipes 232a, 232b, and 232c for supplying three kinds of gases are provided.

  The gas supply pipes 232a and 232c are provided with mass flow controllers 241a and 241c, which are flow rate control devices, and valves 242a and 242c, which are on-off valves, in order from the upstream. A carrier gas supply pipe 234a for supplying a carrier gas is connected to the gas supply pipes 232a and 232c. The carrier gas supply pipe 234a is provided with a mass flow controller 240a, which is a flow rate control device, and a valve 243a, which is an on-off valve, in order from upstream.

  The ends of the gas supply pipes 232a and 232c are connected to the nozzle 300. The nozzle 300 extends in an up-down direction in FIG. 12 in an arc-shaped space between the inner wall of the reaction tube 204 constituting the processing chamber 201 and the wafer 200. A plurality of gas supply holes 302 are formed on the side surface of the nozzle 300. The gas supply holes 302 have the same opening area and are formed at the same opening pitch from the bottom to the top.

  The gas supply pipe 232b is provided with a mass flow controller 241b that is a flow rate control device and a valve 242b that is an on-off valve in order from the upstream. A carrier gas supply pipe 234b for supplying a carrier gas is connected to the gas supply pipe 232b. The carrier gas supply pipe 234b is provided with a mass flow controller 240b that is a flow rate control device and a valve 243b that is an on-off valve in order from the upstream.

  The end of the gas supply pipe 232b is connected to the nozzle 310. The nozzle 310 extends in an up-down direction in FIG. 12 in an arc-shaped space between the inner wall of the reaction tube 204 constituting the processing chamber 201 and the wafer 200. A plurality of gas supply holes 312 are formed on the side surface of the nozzle 310. The gas supply holes 312 have the same opening area and are formed at the same opening pitch from the bottom to the top.

  The nozzle 310 is covered with a quartz nozzle cover 212. The nozzle cover 212 also extends in the up-down direction in FIG. 12 in an arc-shaped space between the inner wall of the reaction tube 204 constituting the processing chamber 201 and the wafer 200. A plurality of gas supply holes 211 are formed on the side surface of the nozzle cover 212. The gas supply holes 211 have the same opening area, and are formed at the same opening pitch from below to above.

  Electrodes 223 and 224 are installed in the nozzle cover 212. The electrodes 223 and 224 are covered with quartz protective tubes 221 and 222. A high frequency generator 226 and a matching box 227 are provided between the electrodes 223 and 224. A constant high frequency (for example, 13.56 MHz) is applied between the electrodes 223 and 224 from the high frequency generator 226, and plasma is formed in the plasma region 225. The high frequency applied between the electrodes 223 and 224 is optimized by the matching box 227. The high frequency generator 226 and the matching box 227 are connected to a controller 280 described later, and the high frequency generator 226 and the matching box 227 are controlled by the controller 280.

In this embodiment, DCS flows into the gas supply pipe 232a, NH ₃ flows into the gas supply pipe 232b, and F ₂ flows into the gas supply pipe 232c. Further, N ₂ flows into the gas supply pipes 234a and 234b.

  Each member such as the mass flow controllers 241a to 241c, 240a to 240b, valves 242a to 242c, 243a, 243b, and 243e, the heater 207, the vacuum pump 246, the boat rotation mechanism 267, and the boat elevator 115 is a controller 280 that is a control unit. It is connected to the.

  The controller 280 adjusts the flow rate of the mass flow controllers 241a to 241c, 240a and 240b, opens and closes the valves 242a to 242c, 243a and 243b, opens and closes the valve 243e and adjusts the pressure, adjusts the temperature of the heater 207, and activates the vacuum pump 246. The stop, the boat rotation mechanism 267 rotation speed adjustment, the lifting operation of the boat elevator 115, and the like are controlled.

  Next, an example of a film forming process using the processing furnace 202 will be described. In this embodiment, an example using the ALD apparatus shown in FIGS. 12 and 13 will be described.

  In the ALD (Atomic Layer Deposition) method, at least two types of reactive gases, which are raw materials used for film formation, are alternately supplied onto a substrate under certain film formation conditions (temperature, time, etc.). This is a technique in which a film is formed by adsorbing on a substrate in atomic units and utilizing a surface reaction. At this time, the film thickness is controlled by the number of cycles in which the reactive gas is supplied (for example, if a film formation rate is 1 liter / cycle, a film formation process is performed 20 cycles when a 20 liter film is formed).

First, the F ₂ etching process will be described.
In the F ₂ etching, the wafer 200 is not loaded into the boat 217 and only the boat 217 is carried into the processing chamber 202. After the boat 217 is carried into the processing chamber 201, processing of the following steps described later is sequentially performed.

(Step 1)
F ₂ gas is used at a concentration of 100% or a concentration diluted with N ₂ by about 20%. The valve 242c is opened, F ₂ gas is caused to flow into the nozzle 300 from the gas supply pipe 232c, and is introduced into the processing chamber 201 from the gas supply hole 302 of the nozzle 300. When diluting and using F ₂ gas, the valve 243a is also opened, and N ₂ is caused to flow from the gas supply pipe 234a into the gas supply pipe 232c. In step 1, the inside of the processing chamber 201 is evacuated in advance, and F ₂ gas is introduced into the processing chamber 201 with the valve 243e opened or closed.

The valve 243e is opened and closed every time a certain time elapses (the valve 243e is repeatedly opened and closed every certain time), and the inside of the processing chamber 201 is etched with F ₂ gas. When the etching is completed, the valves 242c and 243a are closed to evacuate the inside of the processing chamber 201, and then the valve 243a is opened to purge the processing chamber 201 with N ₂ gas.

(Step 2)
In step 2, a plasma process using NH ₃ is performed to remove F ₂ remaining in the process chamber 201.
The valve 242b is opened, NH ₃ gas is introduced into the nozzle 310 from the gas supply pipe 232b, and is introduced into the nozzle cover 212 from the gas supply hole 312 of the nozzle 310. Further, a certain high frequency (for example, 13.56 MHz) is applied between the electrodes 223 and 224 to generate plasma in the plasma region 225 to excite NH ₃ . Then, the plasma-excited NH ₃ is introduced into the processing chamber 201 from the gas supply hole 211 of the nozzle cover 212. At this time, hydrogen radicals are generated by exciting NH ₃ . In Step 2, the valve 243e is kept open, and the inside of the processing chamber 201 is evacuated by the vacuum pump 246.

(Step 3)
In step 3, a Si ₃ N ₄ film is formed on the wafer 200.
The wafers 200 are transferred to the boat 217 and the boat 217 is loaded into the processing chamber 201. Thereafter, film formation is performed by alternately supplying gases according to the ALD method. In this embodiment, film formation is performed by alternately supplying DCS and NH ₃ radicals. Specifically, the valve 242a is opened to allow DCS to flow into the nozzle 300 from the gas supply pipe 232a, and is introduced into the processing chamber 201 from the gas supply hole 302 of the nozzle 300, and then the valve 242a is closed to evacuate the processing chamber 201. Pull.

Next, the valve 242b is opened to allow NH ₃ gas to flow into the nozzle 300 from the gas supply pipe 232b, and is introduced into the processing chamber 201 through the gas supply holes 312 and 211. At this time, a constant high frequency (for example, 13.56 MHz) is applied between the electrodes 223 and 224, and NH ₃ radicals are supplied to the wafer 200. As a result, a Si ₃ N ₄ film is formed on the wafer 200. Thereafter, the application of high frequency between the electrodes 223 and 224 is stopped and the valve 242d is closed to evacuate the inside of the processing chamber 201.

(Step 4)
The process of step 3 is repeated a plurality of times to form a Si ₃ N ₄ film having a predetermined thickness, and when the maintenance time comes, the etching process of step 1 is performed again.

In this embodiment, a gas supply system having the same mechanism as the gas supply pipe 232b, the mass flow controller 241b, and the valve 242b is provided so that H ₂ gas can be introduced into the processing chamber 201 from the gas supply system. Alternatively, H ₂ gas may be supplied to the processing chamber 201 to cause plasma excitation (plasma treatment with H ₂ may be performed instead of plasma treatment with NH ₃ ).

In addition, a remote plasma device is provided outside the processing chamber 201 in place of the electrodes 223, 224, the protective tubes 221, 222, the high frequency generator 226, the matching box 227, etc., and hydrogen plasma from NH ₃ , H _2, etc. is provided in the remote plasma device. It is good also as a structure which generate | occur | produces and supplies it to the process chamber 201. FIG.

According to the present embodiment described above, after supplying the F ₂ gas to the processing chamber 201 in Step 1, the NH ₃ gas is excited by plasma processing in Step 2 to generate hydrogen radicals. F ₂ (F ^* ) reacts with the hydrogen radical and is exhausted from the gas exhaust pipe 231 as HF. Therefore, it is possible to reduce the etching element F, which causes a decrease in the thickness of the Si ₃ N ₄ film, from remaining in the processing chamber 201, and thus to recover the thickness of the Si ₃ N ₄ film. Conventional pre-depot processing is also unnecessary.

  The third embodiment is different from the configuration and processing contents according to the first embodiment mainly in the following points, and is otherwise the same as the first embodiment.

Each gas of DCS, NH ₃ , and F ₂ is introduced into the processing furnace according to the present embodiment. In particular, DCS and NH ₃ are introduced as processing gases during film formation, and F ₂ is introduced during etching. Then, NH ₃ is thermally decomposed as a process after etching.

  As shown in FIGS. 14 and 15, in this embodiment, three gas supply pipes 232a, 232b, and 232c for supplying three kinds of gases are provided. That is, in this embodiment, the gas supply pipe 232d, the mass flow controller 241d, the valve 242d, the carrier gas supply pipe 234c, the mass flow controller 240c, the valve 243c, the nozzle 258, and the gas supply hole 259 described in the first embodiment are not provided. .

In this embodiment, DCS flows into the gas supply pipe 232a, F ₂ flows into the gas supply pipe 232b, and NH ₃ flows into the gas supply pipe 232c. Further, N ₂ flows into the gas supply pipes 234a and 234b.

  Next, an example of a film forming process using the processing furnace 202 will be described. In this embodiment, an example using the CVD apparatus shown in FIGS. 14 and 15 will be described.

First, the F ₂ etching process will be described. In the F ₂ etching, the wafer 200 is not loaded into the boat 217 and only the boat 217 is carried into the processing chamber 202. After the boat 217 is carried into the processing chamber 201, processing of the following steps described later is sequentially performed.

(Step 1)
The same processing as in step 1 of the first embodiment is performed.

(Step 2)
In step 2, NH ₃ is thermally decomposed to remove F ₂ remaining in the processing chamber 201.
The valve 242c is opened, and NH ₃ gas is caused to flow from the gas supply pipe 232c into the nozzle 255 and introduced into the processing chamber 201 through the gas supply hole 256 of the nozzle 255. At this time, NH ₃ receives heat from the heater 207 and is thermally decomposed to generate hydrogen radicals. In Step 2, the valve 243e is kept open, and the inside of the processing chamber 201 is evacuated by the vacuum pump 246.

(Steps 3 and 4)
In steps 3 and 4, the same processing as in steps 3 and 4 of the first embodiment is performed.

According to the above embodiment, after supplying the _{F 2} gas into the processing chamber 201 at step 1, the thermal decomposition process of the NH ₃ in the step 2, the NH ₃ gas by introducing NH ₃ gas into the processing chamber 201 Is excited by the heat of the heater 207 to generate hydrogen radicals, so that F ₂ (F ^* ) remaining in the processing chamber 201 reacts with the hydrogen radicals and is exhausted from the gas exhaust pipe 231 as HF. Therefore, it is possible to reduce the etching element F, which causes a decrease in the thickness of the Si ₃ N ₄ film, from remaining in the processing chamber 201, and thus to recover the thickness of the Si ₃ N ₄ film. Conventional pre-depot processing is also unnecessary.

As mentioned above, although the preferable Example of this invention was described, according to the preferable embodiment of this invention,
A processing chamber for processing the substrate;
An etching gas supply means for supplying an etching gas of any one of a fluorine-based etching gas, a chlorine-based etching gas, or a mixed etching gas in which the fluorine-based etching gas and the chlorine-based etching gas are combined;
Hydrogen radical supply means for supplying hydrogen radicals to the processing chamber;
Control means for controlling the etching gas supply means and the hydrogen radical supply means;
With
There is provided a first substrate processing apparatus in which the control means causes the etching gas supply means to supply the etching gas to the processing chamber, and then causes the hydrogen radical supply means to supply the hydrogen radicals to the processing chamber.

Preferably, the fluorine-based etching gas is an F-containing gas such as NF ₃ gas, F ₂ gas, HF gas, or ClF ₃ gas, and the chlorine-based etching gas is a Cl-containing gas such as BCl ₃ gas.

  Here, in the “hydrogen radical supplying means” of the first substrate processing apparatus, “supplying hydrogen radicals to the processing chamber” means generating hydrogen radicals outside the processing chamber and supplying the hydrogen radicals into the processing chamber. And the meaning of both supplying a hydrogen radical generation source (substance) from outside the processing chamber to the processing chamber to generate hydrogen radicals in the processing chamber.

Preferably,
The hydrogen radical generating means includes
H ₂ O supply means for supplying H ₂ O to the processing chamber;
Heating and excitation means for heating and exciting H ₂ O supplied to the processing chamber;
Have

Preferably,
The hydrogen radical generating means includes
And H ₂ supply means for supplying a H ₂ or hydrogen compound into the processing chamber,
Plasma excitation means for exciting plasma of H ₂ or a hydrogen compound supplied to the processing chamber;
Have

Preferably,
The hydrogen radical generating means includes
A hydrogen compound supply means for supplying a hydrogen compound to the treatment chamber;
Heating / decomposing means for heating and decomposing the hydrogen compound supplied to the processing chamber;
Have

Preferably, in the first substrate processing apparatus,
A processing gas supply means for supplying a processing gas for substrate processing to the processing chamber;
Exhaust means for exhausting the atmosphere in the processing chamber;
With
A second substrate processing apparatus is provided in which the control means controls the processing gas supply means and the exhaust means.

Preferably, in the second substrate processing apparatus,
The substrate accommodated in the processing chamber may be a Si-based film such as a Si ₃ N ₄ film, a SiO ₂ film, or a Poly-Si film, or HfO ₂ by supplying and exhausting a processing gas for processing the substrate. A high dielectric film such as a film or a ZrO ₂ film is formed.

More preferably, in the first and second substrate processing apparatuses,
The temperature of the processing chamber is 300 to 700 ° C., and the pressure of the processing chamber is 1 to 10,000 Pa.

6 is a drawing schematically showing the transition of film thickness after cleaning with F ₂ gas in Si ₃ N ₄ film formation formed by mixing DCS and NH ₃ . It is a schematic diagram plotting the film thickness and the film thickness reduction rate for each batch in the case of an Si ₃ N ₄ film after the etching by F ₂ gas. The film thickness changes in the Si ₃ N ₄ film in the case of performing the NH ₃ plasma process after the etching by F ₂ gas is a diagram showing schematically. It is drawing which shows schematically the process of the method using a predepot. 1 is a schematic view illustrating steps of a method for removing F atoms according to a preferred embodiment of the present invention. 1 is a schematic view illustrating steps of a method for removing F atoms according to a preferred embodiment of the present invention. 1 is a schematic view illustrating steps of a method for removing F atoms according to a preferred embodiment of the present invention. 1 is a perspective view showing a schematic configuration of a substrate processing apparatus used in a preferred embodiment of the present invention. 1 is a side perspective view showing a schematic configuration of a substrate processing apparatus used in a preferred embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is drawing which shows schematic structure of the processing furnace used in preferable Example (Example 1) of this invention, and its accompanying member, Comprising: It is drawing which shows a processing furnace part in a longitudinal cross-section especially. It is sectional drawing which follows the AA line of FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is drawing which shows schematic structure of the processing furnace used in preferable Example (Example 2) of this invention, and its accompanying member, Comprising: It is drawing which shows especially a processing furnace part with a longitudinal cross-section. It is sectional drawing which follows the BB line of FIG. It is drawing which shows the schematic structure of the processing furnace used by preferable Example (Example 3) of this invention, and its accompanying member, Comprising: It is drawing which shows a processing furnace part in a longitudinal section especially. It is sectional drawing which follows the CC line | wire of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Substrate processing apparatus 103 Front maintenance port 104 Front maintenance door 105 Cassette shelf 107 Reserve cassette shelf 110 Cassette 111 Case 111a Front wall 112 Cassette loading / unloading port 113 Front shutter 114 Cassette stage 115 Boat elevator 118 Cassette transfer device 118a Cassette elevator 118b Cassette Transport mechanism 125 Wafer transfer mechanism 125a Wafer transfer device 125b Wafer transfer device elevator 125c Tweezer 128 Arm 134a Clean unit 147 Furnace port shutter 200 Wafer 201 Processing chamber 202 Processing furnace 203 Manifold 204 Reaction tube 207 Heater 208 Boat support table 211 Gas Supply hole 212 Nozzle cover 217 Boat 219 Seal cap 220 O-ring 221, 222 Protective tube 223, 224 Electrode 225 Plasma region 226 High frequency generator 227 Matching box 231 Gas exhaust tube 232a, 232b, 232c, 232d Gas supply tube 234a, 234b, 234c Carrier gas supply tube 240a, 240b, 240c Mass flow controller 241a , 241b, 241c, 241d Mass flow controller 242a, 242b, 242c, 242d Valve 243a, 243b, 243c, 243e Valve 246 Vacuum pump 252, 255, 258 Nozzle 253, 256, 259 Gas supply hole 267 Boat rotation mechanism 280 Controller 300, 310 Nozzle 302, 312 Gas supply hole

Claims (1)

A processing chamber for processing the substrate;
An etching gas supply means for supplying an etching gas of any one of a fluorine-based etching gas, a chlorine-based etching gas, or a mixed etching gas in which the fluorine-based etching gas and the chlorine-based etching gas are combined;
Hydrogen radical supply means for supplying hydrogen radicals to the processing chamber;
Control means for controlling the etching gas supply means and the hydrogen radical supply means;
With
The substrate processing apparatus, wherein the control unit causes the etching gas supply unit to supply the etching gas to the processing chamber, and then causes the hydrogen radical supply unit to supply the hydrogen radical to the processing chamber.

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