WO2004007795A1

WO2004007795A1 - Film formation method for semiconductor processing

Info

Publication number: WO2004007795A1
Application number: PCT/JP2003/008861
Authority: WO
Inventors: Hiroaki Yokoi; Tetsu Zenko; Hiroaki Ashizawa; Tsuyoshi Hashimoto
Original assignee: Tokyo Electron Limited
Priority date: 2002-07-12
Filing date: 2003-07-11
Publication date: 2004-01-22
Also published as: CN1266308C; KR100606398B1; JP2004096060A; KR20040037079A; CN1547624A; JP4393071B2

Abstract

A film formation method for semiconductor processing includes a pre-coat step for coating a placing table (32) by a pre-coat before conveying a substrate (W) to be processed into a processing chamber and a step for conveying the substrate (W) to be processed into the processing chamber (21) after the pre-coat step and forming a main film on the substrate (W) to be processed. The pre-coat step repeats a first and a second step a plurality of times so that a plurality of segment films are superimposed to form a pre-coat. In the first step, a first and a second processing gas are supplied into a processing chamber (21) and a segment film containing a metal element is formed on the placing table (32). In the second step, a second processing gas not containing a metal element is supplied into the processing chamber (21) and a byproduct other than the component to form the segment film generated in the first step is removed from the processing chamber (21) by exhaust of air.

Description

Specification

Film forming method for semiconductor processing

Technical field

The present invention relates to a film forming method for semiconductor processing, and in particular, to a method for forming a CVD (chemi cal vapor

The present invention relates to a method for forming a film containing a metal element by deposi- tion. Here, the semiconductor processing means that a semiconductor layer, an insulating layer, a conductive layer, and the like are formed in a predetermined pattern on a substrate to be processed such as a semiconductor wafer or an LCD substrate. Background of the Invention Means various processes performed to manufacture a semiconductor device and a structure including wiring, electrodes, etc. connected to the semiconductor device.

A semiconductor device having a multilayer wiring structure is manufactured, for example, by repeatedly forming a film and performing pattern etching on the surface of a semiconductor wafer such as a silicon substrate. For example, at a connection portion between a silicon substrate and a wiring layer thereabove or a connection portion between upper and lower wiring layers, a barrier layer is formed to prevent exfoliation of an underlayer or to suppress mutual diffusion of material between upper and lower layers. Is formed. As the barrier layer, for example, a TiN film formed by thermal CVD is used. As a base film of the TiN film, a thin Ti film may be formed by plasma CVD or not.

FIG. 11 is a schematic diagram showing a conventional CVD apparatus for forming a barrier layer. This apparatus has a vacuum processing chamber 1 made of, for example, aluminum. An exhaust port 1 1 is provided on the bottom of processing chamber 1. It is formed. A mounting table 13 for mounting the semiconductor wafer W horizontally is provided inside the processing chamber 1. The mounting table 13 is made of, for example, aluminum nitride and has a built-in heater 12. A shower head 15 for supplying a processing gas is provided so as to face the mounting table 13. On the lower surface of the shower head 15, a large number of gas ejection holes 14 are formed at positions facing the wafer W mounted on the mounting table 13. During film formation, the T i C 1 ₄及Pi NH ₃ supplied wafer W mounted on the mounting table 1 3 is the process gas from Shah Wae' de 1 5 while being heated by the heater 1 2 At this time, the reaction of the following equation (1) occurs, and a thin film of TiN is formed on the entire surface of the wafer W.

6T1CI4 + 8NH3 → 6TiN + 24HCl + N ₂ '(1)

When such a film forming process is repeatedly performed on a plurality of wafers W, the TiN adheres to a wall or the like in the vacuum processing chamber 1. In particular, around the mounting table 13 having a high temperature, for example, as shown in FIG. 12, the deposit 16 is gradually laminated. For this reason, the thermal emissivity of the surface of the mounting table 13 changes, and even if the set temperature is the same, a difference occurs in the surface temperature of the mounting table 13 and uniformity of the film thickness between the wafer surfaces is reduced. To avoid this problem, for example, a TiN film is formed in advance on the entire surface (upper surface, lower surface, and side surface) of the mounting table 13 before performing the film forming process on the wafer W. A process called pre-coating is performed. For the TiN film (pre-coating) formed by this pre-coating process, the above problem can be avoided if the thickness is, for example, 0.5 μm or more. This is known. In addition, this pre- When a film is formed on the wafer w, the wafer W is formed by an aluminum material constituting the processing chamber 1 and a ceramic material constituting the mounting table 13 such as metal impurities such as A1 in A1N. Pollution is also suppressed.

The conventional pre-coating process is performed as follows. First, the inside of the vacuum processing chamber 1 is evacuated and the temperature of the mounting table is set to 600 to

Heat to 0 ° C. When the temperature of the mounting table 13 is stabilized, the pressure in the vacuum processing chamber 1 is set to 40 Pa (0.3 T rr). After the gas flow is stabilized by pre-flow, T

The 1 C 1 ₄ gas, for example, supplying the NH 3 gas at 3 0 ~ 5 0 sccm flow rate of about, for example, a 4 0 0 sccm flow rate of about at each simultaneously vacuum processing chamber 1. The feeding of both the process gas, For example, after about 1 5 minutes to 2 0 minutes for a post Tokyo tri de treatment, by stopping the supply of T i C l ₄ gas, NH ₃ gas only, For example, while supplying at a flow rate of about 100 sccm, the inside of the vacuum processing chamber 1 is evacuated for a predetermined time, for example, several tens of seconds, whereby the surface of the mounting table 13 is For example, a TiN film (pre-coat) of about 0.5 to 2.0 / m is formed. Thereafter, the wafer W is placed on the pre-coated mounting table 13, and, for example, a T i film 18 and a T i N film 19 are formed on the surface of the wafer W by each film forming method. (See Figure 13).

However, in the long et film formation method of the T i N film, T i C 1 ₄ to Gasukaゝet dissociation in the pre-co over preparative process, or by-formed salt compound reacts with the metal in the vacuum processing chamber 1 Metal chloride is produced. This metal chloride evaporates during the film forming process, It is taken into the film on W. Unexpected metal contamination in the film will adversely affect the electrical properties of the device and reduce yield. For this reason, the amount of metal contamination must be minimized. The permissible limit of metal contamination will become more severe as devices become thinner.

Disclosure of the invention

An object of the present invention is to reduce the total amount of impurities such as metals in a main film formed on a substrate to be processed after a pre-coating process on a mounting table in a processing container in a film forming method for semiconductor processing. It is here.

A first aspect of the present invention is a film forming method for semiconductor processing for forming a film containing a metal element on a substrate to be processed mounted on a mounting table in an airtight processing chamber,

(a) a pre-coating step of coating the mounting table with a pre-coat before loading the substrate to be processed into the processing chamber;

A first processing gas containing the source gas containing the metal element is supplied into the processing chamber while heating the mounting table and exhausting the processing chamber, and the segment film containing the metal element is placed on the mounting table. A first step of forming;

A second processing gas that does not contain a raw material gas containing a metal element is supplied into the processing chamber while heating the mounting table and exhausting the processing chamber, and the segment film generated in the first step is provided. A second step of removing, by exhaust, by-products other than components that form a gas from the processing chamber; Repeating the first and second steps a plurality of times to form a pre-coat by laminating a plurality of segment films;

Having

(b) after the pre-coating step, a film forming step of loading the substrate to be processed into the processing chamber and forming a main film on the substrate to be processed;

Loading the substrate to be processed into the processing chamber and placing the substrate on the mounting table;

The first and second processing gases are supplied into the processing chamber while heating the mounting table and exhausting the processing chamber to form the main film containing the metal element on the substrate to be processed. Having a process and

Is provided.

According to a second aspect of the present invention, a first treatment including the metal element is performed in the treatment chamber in order to form a film containing the metal element on a substrate to be processed placed on a mounting table in an airtight treatment chamber. A CVD method for forming a film containing the metal element on the substrate to be processed while supplying a gas and a second processing gas for assisting the decomposition of the first processing gas,

The first and second processing gases are supplied into the processing chamber while heating the mounting table and exhausting the processing chamber. A first step of forming a segment film containing the metal element on a table,

While stopping the first processing gas, heating the mounting table and exhausting the processing chamber while supplying the second processing gas into the processing chamber to decompose or react the first processing gas. Reacting the intermediate produced by the above with the second processing gas to generate a by-product, and removing the by-product from the processing chamber by exhaustion; and

Repeating the first and second steps a plurality of times, thereby stacking a plurality of segment films to form the pre-coat;

Wherein substantially the same processing temperature and processing pressure are used in the first and second steps, and the by-product sublimates at the processing temperature and processing pressure.

(b) after the pre-coating step, a film forming step of carrying the substrate to be processed into the processing chamber and forming a main film on the substrate to be processed; and

Loading the substrate to be processed into the processing chamber and mounting the substrate on the mounting table;

The first and second processing gases are supplied into the processing chamber while heating the mounting table and exhausting the processing chamber to form the main film containing the metal element on the substrate to be processed. Having steps and.

Is provided.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a longitudinal sectional view showing a CVD apparatus according to the first embodiment of the present invention.

2A to 2C are diagrams showing a film forming method according to the first embodiment in the order of steps.

FIG. 3 is a diagram showing, in chronological order, control of gas supply / discharge and pressure control in a pre-coating process used in the film forming method according to the first embodiment.

FIG. 4 is a diagram showing, in a time series, gas supply and pressure control in a pre-coating process used in a film forming method according to a modification of the first embodiment.

FIG. 5 is a view showing experimental results regarding the film forming method according to the first embodiment.

FIG. 6 is a longitudinal sectional view showing a CVD device according to a second embodiment of the present invention.

FIG. 7 is a view showing processing conditions of each step in a pre-coating process used in the film forming method according to the second embodiment.

FIG. 8 is a diagram showing the relationship between the number of repetitions of the precoat sequence and the Fe concentration in the film forming method according to the second embodiment.

Fig. 9 shows the processing conditions of each step in the purge process after idling (long stop).

FIG. 10 is a diagram showing experimental results regarding the purge process shown in FIG. 9; FIG. 11 is a schematic diagram showing a conventional CVD apparatus.

Figure 12 is a diagram for explaining the problems of the conventional technology.

Figure 13 is a diagram for explaining the problems of the conventional technology.

BEST MODE FOR CARRYING OUT THE INVENTION 3 008861

8 In the course of developing the present invention, the present inventors conducted research on the problems of the conventional film forming method performed by the CVD apparatus shown in FIG. As a result, the following findings were obtained.

In the deposition process of the TiN film, the inner surface of the processing chamber 1 and the surface of the chassis head 15 are lower in temperature than the mounting table 13 so that the TiN film is not attached or Almost no. However, when the distance between the shower head 15 and the mounting table 13 is short, a film may be formed on the shower head 15. In the film forming process of T i N film, a mixed gas of T i C 1 ₄ gas or T i C 1 4 gas and NH ₃ gas, for example, flow is long time 1 5-2 0 minutes. In this case, Ri by the thermal decomposition of T i C 1 ₄ gas, or. T i C 1 4 gas and NH ₃ by Ri hydrogen chloride in the reaction between the gas (HC 1) is generated. HC 1 reacts with the surface of the metal part such as the processing chamber 1 to generate a large amount of metal chloride. This metal chloride diffuses during film formation on the wafer W and is taken into the thin film on the wafer W, which is one of the factors that increase the amount of metal contamination.

Metal compounds are formed during pre-coating, which results in

The problem of the incorporation of the impurity metal into the thin film formed on W also exists in addition to the process of forming the TiN film. For example, when a Ta 2 O 5 film is formed by reacting PET (inter-ethoxy tantalum) with θ ₂ gas, a pre-coat is formed on the surface of the mounting table in advance. In this case, the stable metal chloride in the processing chamber reacts with the processing gas in the pre-coating process, becomes an unstable substance, and diffuses into the processing chamber. In addition, this metal chloride is used as a table of the C 1 F ₃ gas used in the cleaning process and the metal parts such as the processing chamber 1. It is thought that it was generated by the reaction with the surface.

Hereinafter, embodiments of the present invention configured based on such knowledge will be described with reference to the drawings. In the following description, components having substantially the same functions and configurations are denoted by the same reference numerals, and repeated description will be made only when necessary.

(First Embodiment)

FIG. 1 is a schematic diagram showing a CVD device according to a first embodiment of the present invention. This apparatus has, for example, a cylindrical vacuum processing chamber 1 made of aluminum. At the center of the bottom surface of the vacuum processing chamber 21, a concave portion forming the exhaust chamber 23 is formed. The side surface of the exhaust chamber 23 is connected via an exhaust pipe 24 to a vacuum exhaust unit 25 for maintaining the inside of the processing chamber 21 at a predetermined vacuum pressure. A gate valve 26 for carrying in / out the wafer W is provided on a side wall of the processing chamber 21.

Inside the processing chamber 21, there is provided a disk-shaped mounting table (susceptor) 32 supported on the lower side by a column 31 extending upward from the bottom of the exhaust chamber 23. You. The mounting table 32 is made of a ceramic material, for example, aluminum nitride (A1N). The upper surface of the mounting table 32 is formed to be slightly larger than the wafer W to be processed and to be able to mount the wafer W substantially horizontally. The outer edge of the table 3 2 covers the mounting table 3 second surface toward the side surface from the upper surface, cormorants rows guide the wafer W, for example, Ryo Lumi Na (A 1 ₂ O ₃₎ good Ri becomes Guy Dori 3 is installed.

For example, a resistance heating element is used inside the mounting table 32. Heaters 34 are buried. The temperature of the heater 34 is controlled by, for example, a power supply unit 35 provided outside the processing chamber 21 in accordance with each application. This makes it possible to uniformly raise the temperature of the entire surface of the wafer W in a film forming process described later, or to raise the surface of the mounting table to a predetermined temperature in a pre-coating process.

A lift pin 36 (actually, a transfer pin) for transferring a wafer W to and from a transfer arm (not shown) that has entered through the gate valve 26 is provided on the mounting table 32. There are, for example, three). The lift bin 36 is supposedly protruding from the stand 32. The lifting and lowering of the lift bins 36 is performed by the function of the lifting and lowering mechanism 38 via a support member 37 that supports the lower ends thereof.

A shower head 4 is provided on the ceiling of the processing chamber 21 via an insulating member 41. The shower head 4 is installed independently of each other while preventing the two gases from mixing with each other inside the shower head. The structure of the loop. The shower head 4 has a configuration in which, for example, three plate-like parts (upper section 4a, middle section 4b, lower section 4c) made of aluminum or nickel are vertically stacked. . The first flow path 42 connected to the first gas supply pipe 5a, and the second flow path 43 connected to the second gas supply pipe 5b are each composed of a part 4a, 4b. , 4c. A space for gas diffusion is provided between the parts, and communicates with the gas ejection holes 44 and 45 formed on the lower surface of the lower portion 4c through the space. The supply of gas to the first and second gas supply pipes 5a and 5b is performed from a gas supply mechanism 50 arranged on each upstream side. The gas supply mechanism 50 includes a cleaning gas supply source 51, a film formation gas supply source 52, a first carrier gas supply source 53, an ammonia gas supply source 54, and a second carrier gas supply source. A rear gas supply source 55 is provided. The cleaning gas supply source 51 supplies a cleaning gas, for example, a C 1 F ₃ gas. The film forming gas supply source 52 supplies a titanium tetrachloride (TiCl ₄ ) gas, which is a processing gas containing Ti as a film forming component. The first carrier gas supply source 53 supplies a gas used as a carrier when the TiC 14 gas is supplied, for example, an inert gas such as a nitrogen (N 2) gas. The ammonia gas source 54 supplies ammonia (NH 3) gas. The second carrier gas supply source 55 supplies a carrier gas used when supplying NH ₃ gas, for example, N ₂ gas.

Valves V1 to V10, mass flow controllers Ml to M5, and the like are provided in the piping of the gas supply mechanism 50. From the first gas supply source 5a, a bypass 5c for exhausting gas directly to the exhaust pipe 24 without passing through the processing chamber 21 is branched. By switching the valves Va and Vc, gas flows to the processing chamber 21 or the bypass path 5c.

As will be described later, NH ₃ gas is used as a “processing gas for forming a segment film” in the pre-coating process and is used as a “processing gas for removing metal chlorides”. Also used as "gas." The T i C 1 ₄ gas treatment comprising "metal compound Chemical gas "and" process gas which is a compound containing a metal and a halogen element ".

The shower head 4 is connected to an RF (high frequency) power supply section 47 via a matching box 46. The RF power supply unit 47 converts the film forming gas supplied to the wafer W into a plasma during the film forming process, and promotes the film forming reaction. The drive control in the elevating mechanism 38, the output control of the power supply section 35, the adjustment of the exhaust flow rate in the vacuum exhaust section 25, and the gas supply and cutoff and flow rate adjustment in the gas supply mechanism 50 are performed. The adjustment of each member constituting the membrane device is controlled by a control unit (not shown) including a computer and the like. These controls are performed according to a recipe prepared in advance in the control unit.

Next, taking a case where a titanium nitride (TiN) film is formed on the surface of the wafer W as an example, a film forming method using the above-described apparatus will be described with reference to FIGS. 2A to 2C and FIG. This is explained with reference to 3. 2A to 2C, illustration of the guiding 33 is omitted for convenience.

Prior to the deposition process on the wafer W, T i C 1 ₄ gas及Pi NH 3 pre co over preparative process gas in table 3 second surface with a thin film of T i N is performed. Since this pre-coating process is to form, for example, a TiN film on the entire surface of the mounting table 32, the pre-coating process is performed without loading the wafer W into the processing chamber 21.

First, the pressure control valve is fully opened by the evacuation unit 25 to evacuate the processing chamber 21. The first and second carrier gas supply sources 53 and 55 are supplied with an inert gas, for example, N 2 gas at a flow rate of, for example, 5 OO sccm. According to heater 3 4 The mounting table 32 is heated to a predetermined temperature, for example, about 600 ° C. to about 700 ° C. Further, N ₂ gas is supplied as a sheath gas into the support 31 of the mounting table 32 from a gas supply mechanism (not shown) at a flow rate of, for example, about 300 sccm. The inside of the column 31 is made to have a positive pressure by using the sheath gas, and the processing gas is prevented from entering the column 31 where the wiring for taking out the heater 34 embedded in the mounting table 32 is arranged. In addition, make sure that the wires and terminals in the column 31 are not corroded. The supply of this sheathed gas will be continued thereafter.

FIG. 3 is a diagram showing, in chronological order, control of gas supply and supply pressure in a pre-coating process used in the film forming method according to the first embodiment.

When the temperature in the processing chamber 2ί is stabilized by the above-described process, the supply of both processing gases is turned on at time t1, and the first gas supply pipe 5a and the other gases are used as TiC14 gas. And the supply of N ₂ gas, and the supply of NH ₃ gas from the second gas supply pipe 5b, respectively. During the supply of these processing gases, the processing chamber 21 continues to be evacuated. Order to T i C 1 ₄ Stabilization of the gas flow rate for the supply of gas, first, the time t 1 forceゝal, for example, 1-6 0 seconds, without using the this Kodewa 1 0 seconds processing chamber 2 1 Baino ,. A pre-flow is made to flow to the exhaust side through the water path 5c. Thereafter, T i C 1 ₄ gas, the valve V a, to scan the V b reaches the time t 2 between this switch the flow channel Direction of gas, for example, 5-9 0 seconds, this Here, it is supplied into the processing chamber 21 for 30 seconds. On the other hand, for the supply of NH 3 gas, from time t 1 to t 2, for example, It is supplied into the processing chamber 21 continuously for 10 to 120 seconds, here 40 seconds. Therefore, the T i C 1 ₄ gas and NH ₃ gas into the process chamber 2 within 1 simultaneously, for example, 5 to 1 2 0 seconds, preferred properly supplied 1 0-6 0 seconds. .

Ri by the supply of the Yo I Do T i C 1 ₄ gas and NH ₃ gas described above, Remind as in FIG. 2 A, the pre-coat film of the first T i N the entire surface of the table 3 2 (Segment film) is formed (first step: segment film formation step). Here, the pressure in the processing chamber 21 is maintained at, for example, 13.3 to 133.3 Pa (0.1 to 1.OTorr) from time t1 to time t2. Is done. Range of gas flow rate, for example, T i C 1 ₄ gas force S 5 ~; L 0 0 sccm , the preferred properly Ri 3 0 ~ 8 0 sccm about der, NH ₃ gas force 5 0 ~: L 0 0 0 sccm, preferably about 200 to 800 scc ai. The processing temperature is, for example, about 300 to 700 ° C., and preferably 400 to 600 ° C.

In this step, the TiC 14 gas and the NH ₃ gas react as shown in the above-described equation (1), and a TiN film is formed on the surface of the mounting table 32. On the other hand, the inner wall of the processing chamber 21 and the surface of the shower head 4 are lower than the processing temperature. For this reason, the reaction of equation (1) does not substantially occur on these members, and both processing gases are exhausted in a gasified state, and the TiN film is not deposited. Subsequently to stop the supply of T i C 1 ₄ gas及Pi NH ₃ gas at time t 2, the vacuum evacuation processing chamber 2 1. In this case, for example, N ₂ gas may be supplied.

Thereafter, Remind as in FIG. 2 B, stop the supply of T i C 1 ₄ Gas While stopped, the NH 3 gas is supplied at a flow rate of, for example, 500 to 200 sccm, for example, for 1 to 60 seconds, preferably 5 to 20 seconds, and here for 30 seconds. (Second step: metal chloride removal step). In addition, in addition to NH ₃ , N ₂ gas as a carrier gas is also supplied. At this time, the vacuum exhaust of the processing chamber 21 is continued. This ensures that the pressure in the treatment chamber 2 in 1, For example, 1 3 3. 3 ~ 6 6 6. 5 c then a P a (l ~ 5 T orr ), stops the supply of the NH ₃ The inside of the processing chamber 21 is evacuated to remove residual NH ₃ gas in the processing chamber 21. At this time, for example, N ₂ gas may be supplied. One cycle ends at time t3.

Thereafter, the cycle of the process from time t1 to t3 is repeated a plurality of times, for example, at least 10 cycles / hour, preferably at least 30 cycles. As a result, the segment films are stacked to form a pre-coat. The number of cycles is appropriately adjusted depending on the thickness of the thin film formed in one cycle.

By supplying only the NH ₃ gas during the segment film forming process in the pre-coating process, the chloride component generated in the segment film forming process is removed from the processing chamber 21. Is done. Here, the mechanism by which the chlorine component in the processing chamber 21 is removed is considered to be as follows. In other words, unreacted compound of formula T i C 1 X (X is an arbitrary natural number) dissociated T i C 1 ₄ monthゝet Te reaction smell (1) or, chlorides processing chamber as a by-product Reacts with metal members to generate metal chlorides. This metal chloride is reduced by NH ₃ gas, and is produced in this reduction reaction. The reacted HC 1 reacts with NH ₃ to produce ammonium chloride (NH ₄ C 1). By-products such as HC 1 and NH ₄ Cl 未 Unreacted substances such as Ti C 1 X sublime at the above-mentioned processing temperature, and therefore do not adhere to the inner wall surface of the processing chamber 2. It is exhausted as it is.

By performing pre-coating (so-called cycle pre-coating) on the entire surface of the mounting table 32 in the above steps, for example, a TiN film having a film thickness of about 0.7 is obtained. Film is formed on 32. Thereafter, the temperature of the mounting table 32 is maintained at about 400 to 700 ° C. by the heater 34 to evacuate the processing chamber 21, and the gate valve 26 is opened. Open and transfer wafer W into processing chamber 21 by the transfer arm (not shown). Next, the wafer W is mounted on the upper surface of the mounting table 32 (on the pre-coat) by the cooperation of the transfer arm and the lift bin 36, and the gate valve 26 is closed. Then, the process shifts to a film forming process (film forming process) on the wafer W.

In the film forming step, as shown in FIG. 2C, while the processing chamber 21 is evacuated, a TiCl ₄ gas and an NH ₃ gas are supplied to the wafer W mounted on the mounting table 32. Supply. At this time, a processing temperature of about 400 to 700 ° C. and a processing pressure of about 100 to 100 Pa are used. This process is continued until a TiN film having a desired thickness is obtained. Specifically, for example, the processing temperature is set at 680 ° C., the pressure is set at 667 Pa, and the film formation time is determined according to the target film thickness because the film thickness is proportional to the film formation time. Is set as appropriate. Also, at this time, in order to increase the responsiveness as needed, an RF power source of 47 kHz, 450 kHz to 60 MHz, preferably 450 kHz is used. An RF power of 200 to 100 W, preferably 200 to 500 OW, is supplied at a frequency of 1 to 3.56 MHz to plasma-process the processing gas to form a film. You may go. In this case, the processing temperature is about 300 to 700 ° C., preferably 400 to 600 ° C.

After completion the formation of T i N film to the wafer W surface, to stop the supply of both the processing gas T i C 1 ₄及Pi NH _3, for example, performs a 1 0 second Ho purge throat treatment chamber 2 1 . Next, NH ₃ gas is supplied to the processing chamber 21 along with N ₂ gas as a carrier gas to perform post-nitride processing on the surface of the TiN film on the wafer W. In this way, a film formation process is repeatedly performed on a predetermined number of wafers W in the same process.

After processing a predetermined number of wafers W, the temperature of the mounting table 32 is set to, for example, 200 ° C. in order to remove unnecessary film formation adhered to the processing chamber 21. Cleaning is performed by supplying C 1 F 3 gas into the processing chamber 21. Thereby, the pre-coat formed on the surface of the mounting table 32 is also removed. Thereafter, when the film formation process is performed again on a predetermined number of wafers W, the above-described processes are performed again from the pre-coating process.

According to the present embodiment, as will be apparent from the results described later, metal used for components such as the processing chamber 21 and the shower head 4 is taken into the TiN film formed on the wafer W. Intrusion can be greatly reduced.

In conventional pre-coat and continue to long flow and T i C 1 ₄ gas and NH ₃ gas is a process gas continuously. Thus, unreacted substances and by-product of T i C 1 X generated Ri by the decomposition of the T i C 1 ₄ Chlorides such as HC 1 and NH 4 CI as products exist in the processing chamber 21 and in the precoat. It is presumed that these chlorides react with metal parts in the processing chamber 21 to generate metal chlorides and enter the film on the wafer W during the film forming process.

On the other hand, in the present embodiment, the TiC 14 gas and the NH ₃ gas are supplied into the processing chamber 21 to form a thin precoat (segment film) on the mounting table 32. and, except for the following NH 3 gas flowed metal chloride Ri Installing by the and this change in the gas HC 1 and NH ₄ C 1. These two steps are regarded as one cycle, and this process is performed for several tens of cycles to form a pre-coat having a desired film thickness. For this reason, the amount of metal chloride generated in the processing chamber 21 is suppressed, and the amount of metal mixed in the film of the wafer W is reduced.

In other words, in the present embodiment, instead of performing film formation continuously for a long time, film formation of a segment film and removal of chloride (purge, exhaust) which are performed in a short time are repeated. To form a pre-coat. Therefore, the amount of chloride generated per process is suppressed, and the amount of chloride remaining in the processing chamber 21 is small.

Through experiments, the chlorine concentration as chloride in the processing chamber 21 at the end of pre-coating was compared between the conventional method and the present invention. As a result of this experiment, the chlorine concentration was about 2 to 3 atoms in the conventional method. / ₀ was high. In the present embodiment, the chlorine concentration was reduced to approximately ◦ .1 atomic%. That is, it was confirmed that the production amount of the metal chloride can be suppressed according to the present embodiment.

It is not necessary to supply NH 3 gas intermittently in the pre-coating process. In pre-coating, N ₂ gas Supply may not be continued after time t1 in the above embodiment. FIG. 4 shows an example of this case, following FIG. Note that the conditions such as the flow rate and the pressure are the same as those in the above-described embodiment, and the description is omitted here.

First, purging with N ₂ gas is performed until time t 1 when the temperature in the processing chamber 21 stabilizes. To become the time t 1 is turned ON to supply the T i C 1 ₄ gas及beauty NH ₃ gas, and OFF the supply of N ₂ gas. Time tl after the NH ₃ gas ON, intends rows intermittently supplied only T i C 1 4 gas while the OFF N ₂ gas. This cycle is repeated up to a predetermined number, for example, 30 cycles. Even in such a method, the chloride in the processing chamber or in the film is removed by NH ₃ gas between the time t 2 and the time t 3. Further, since the film formation of the precoat is repeated, the same effect as in the above-described case can be obtained.

In the method described with reference to FIG. 3 or FIG. 4, an example is given in which a TiN film is formed in both the pre-coating and film-forming steps. The type of film to be formed on the pre-coat and the wafer W can be a Ti film.成膜成膜 When a film is formed, for example, TiC 14 gas and hydrogen (H ₂ ) gas are used as processing gases, and in addition to these, anoregon gas is used as a plasma gas. (Ar) gas is used. Specifically, the above three types of gases are supplied into the processing chamber 21 at a film forming temperature of 700 ° C. and a pressure of 133 Pa (liter). To shower the head 4 indicia force Π the RF voltage, the reduction reaction of the T i C 1 ₄ gas and H ₂ gas and this into plasma the A r gas is promoted. As a result, A T i film is formed on the table 32 or the surface of the wafer W. The gas flow rate at this time is, for example, TiC 14 gas power S 1 to 200 sccm, H ₂ gas power 1 to 2 liters / min, and Ar gas 1 liter Z min It is about.

As described above, the Ti film can be used for the pre-coating of the mounting table 32 and the film formation of the wafer W. For this reason, the present embodiment is applied to the following processes. The present invention can be applied to four patterns of coating + Ti film formation and precoating of Ti film + Ti film formation. When forming the TiN film, the Ti film may be formed as a base film prior to forming the TiN film (including during pre-coating). Good.

In each of these cases, the reaction gas used to remove chlorides was NH ₃ gas, and the same process as described with reference to FIG. 3 or 4 was repeated several times. A similar effect can be obtained. The gas for removing metal chlorides is not limited to NH ₃ gas, but may be any gas that can produce ammonium halide. For example, a gas containing nitrogen and hydrogen, for example, a hydrazine-based gas such as N ₂ H ₂ can be used. N ₂ , H ₂ gas, and NH ₃ gas may be supplied in appropriate combination, and may be turned into plasma. In any case, the same effect as the method described with reference to FIG. 3 or FIG. 4 can be obtained.

In order to confirm the effect of the present embodiment, a comparative experiment was performed between the conventional method described in [Background Art] and the method of the example according to the present embodiment. Was done. In this experiment, the processing temperature was 680 ° C., the processing pressure was 40 Pa, the flow rate of TiCl ₄ gas was about 30 to 50 sccm, and the flow rate of NH 3 gas was about 400 sccm. In the conventional method, a film formation process (as an alternative to the pre-coating process) was performed on a wafer while continuously flowing a processing gas for 10 to 15 minutes. In the method of this embodiment, as described above, a plurality of cycles are repeated to perform a film formation process on a wafer (as an alternative to a pre-coat process). In both methods, the target film thickness was 0.7 / • im.

FIG. 5 is a diagram showing the results of measuring and comparing the amount of metallic impurities (the number of atoms per unit area) in the TiN film formed by both of the above methods. In FIG. 5, white bars indicate the conventional method, and hatched bars indicate the method of the embodiment. As shown in FIG. 5, in the method of the embodiment, the amount of metallic impurities in all the items of A1, Cr, Fe, Ni, Cu, and the total amount was lower than in the conventional method. Few. From this result, it was found that the metal contamination was reduced by the film forming method according to the present embodiment. As described above, according to the pre-coating treatment according to the present embodiment, the amount of chloride in the treatment chamber 21 also decreases, so it is presumed that there is a correlation between the two. .

The present embodiment is not limited to the T i and T i N films, but may be applied to other thin films formed by a gas phase reaction using a gas of a metal compound containing a metal constituting a film forming component and a halogen. Applicable. For example, using WF6 (Tungsten hexafluoride) gas and H2 gas (sometimes using SiH4 gas) to produce W ( N) It is applicable when a film is formed. WF ₆ gas and S i H ₂ C 1 ₂ (Axis B Noreshi run-) Ru applicable der even in the case of forming the WS i ₂ (data Ngusute Nshi Li Sai de) film have use a gas. Further, T a B r ₃ or T a C l ₃ and the case of forming a T a film using a gas and H ₂ gas, T a B r ₃ or T a C 1 3 gas, NH ₃ or NH ₃ and it is also applicable to a case of forming a T a N film using the H ₂ gas.

Furthermore, the present embodiment is not limited to using a metal compound gas containing a metal and a halogen, but is also applicable to a case where a pre-coat is formed using an organometallic gas. For example, P E T

(Bae printer d preparative Kishita Ntanore: T a (OC 2 H 5) 5) and 0 T a ₂ 〇 ₅ (oxide motor te le) with ₂ gas film when the film on the wafer, PET and 〇 A pre-coat is formed using two gases. In this case, unreacted carbon compounds dissociated from PET or C

By-products containing (carbon) enter the processing chamber or into a thin film (brick film), and a small amount of this C is incorporated into the surface of the wafer W during the process. Therefore Te pre Coat treatment odor already Ni would Yo of the sequence shown in FIG. 3, the step of flowing the PET and 0 ₂ gas simultaneously, then repeat the cyclic Kunore comprising the step of flowing the O ₂ gas only return. Thus, during the period in which only the O 2 gas flows, the O ₂ gas reacts with C contained in the processing chamber or the carbon compound or by-products to form carbon dioxide and discharge C. Can be done.

(Second embodiment)

FIG. 6 is a schematic view showing a CVD apparatus according to the second embodiment of the present invention. It is a schematic diagram. The device is composed of Ni Let 's you forming a T a ₂ 0 ₅ film on the wafer. In the following, the case where the shape forming the pre-co over preparative onto table using PET and 〇 ₂ gas as a source gas containing a metal element, then forming a T a ₂ 0 ₅ film on a wafer, © A method for reducing metal contamination on a wafer will be described. The method of this is Ri per To form the pre-co-chromatography preparative, and simultaneously supplied to the processing chamber PET and 〇 ₂ gas, followed by an inert gas, for example, the process chamber Ri by the N 2 (nitrogen gas) In this method, a series of steps of purging and finally evacuating the processing chamber are repeated several times.

In the film forming apparatus shown in FIG. 6, since PET is liquid at room temperature, it flows out of the PET supply source 61 as a liquid, is vaporized by the vaporizer 62, and is supplied into the processing chamber 21. . O ₂ gas is supplied from source 63. In order to bypass the vacuum processing chamber 21, a bypass path 5 c is provided, the downstream side of which is connected to the exhaust pipe 24. By switching between the valves Vb and Vc, the state in which the PET gas and N2 gas flowing through the _second gas supply pipe 5b are supplied into the processing chamber 21 and the processing chamber 2 Switched to a state where exhaust bypasses 1 and is exhausted.

T a ₂ O 5 film matching unit 4 6 and the RF power supply unit 4 7 for generating plasma has been used in Figure 1 because they are generated Ri by the thermal decomposition of PET is not provided. As for the other parts, those having the same reference numerals in FIG. 1 indicate the same parts, and the description of each part is the same as the structural description in FIG.

In order to heat the substrate to be processed, a heating structure using a known lamp should be adopted instead of the resistance heating heater provided on the mounting table. Can be. In this case, the mounting table is heated by a heating source consisting of a lamp disposed below the mounting table. When the lamp heating method is adopted, as a material of the mounting table, for example, SiC (silicon carbide) having a thickness of about 7 mm is preferable.

Next, a film forming method according to the second embodiment will be described. FIG. 7 is an explanatory diagram showing a gas flow rate and the like during a pre-coating process in the film forming method according to the second embodiment. In FIG. 7, "5a:" means that gas flows through the first gas supply pipe 5a. “5b:” means that the gas flows through the second gas supply pipe 5b. “5c:” is vino. Means that gas flows through the road 5c. In the following steps S1 to S5, the evacuation of the processing chamber 21 is continued. First, in step S1, the temperature of the mounting table is heated to 445 ° C., N ₂ gas is supplied into the processing chamber 21 from the first gas supply pipe 5a, and the pre-coating step is performed. . Following step S 2 flow rate of odor Te the N ₂ gas: 0 ₂ gas with reduced to looo sccm force et 6 0 0 sccm is supplied at a flow rate of 4 0 0 sccm into the processing chamber 2 1. On the other hand, in step S 1 and 2, the second supply pipe 5 b force We PET gas及Pi N ₂ gas is pre flow, is evacuated and through the bypass passage 5 c without passing through the processing chamber 2 1 It is.

In this case, the preflow of the PET in step S1 is performed with a flow meter tolerance of 90 mg ± 15 (10 to 15) mg of flow rate control. On the other hand, the preflow of PET in step S2 is performed with a flow meter tolerance of 90 mg ± 5 (3 to; LO) mg of flow rate control. Therefore, PET can be more stably supplied into the processing chamber. The preflow of PET in step S2 is performed once, and can be performed for a predetermined time, for example, 20 seconds or more, and preferably 30 seconds or more.

Thereafter, in step S3 (a step of forming a segment film), the supply of the N ₂ gas from the first gas supply pipe 5a is stopped, and the second gas supply pipe 5b is connected. The pre-flowed PET gas and N ₂ gas that have flowed are supplied into the processing chamber 21. By performing the pre-flow before the film formation in this way, a processing gas can be supplied at a stable flow rate from the start of the process S3. In addition, by keeping the gas flow rate in the processing chamber 21 constant (for example, the total flow rate is 100 sccm) until the steps S1 to S3, the internal pressure of the processing chamber 21 changes. Therefore, fluctuations in the temperature of the mounting table 32 and the wafer temperature caused by the fluctuation can be suppressed.

In here, Ri by the time the process S 3 to and this turned into cormorants good the next, the film thickness Ru can and child to adjust the deposited segmenting door film (T a ₂ 0 ₅ film). In the present embodiment, when the time of step S3 is set to 58 seconds, 71 seconds, 141 seconds, and 281 seconds, the thickness of the segment film becomes approximately 5.2 nm and 6 nm, respectively. 5 nm, 13 nm and 26 ηm.

In the processes SI to S3, the pressure in the processing chamber 21 is changed and set within a range of approximately 13.3 to 1333 Pa, preferably approximately 39.9 to 667 Pa. can do. Further, the processing temperature can be changed and set within a range of about 300 to 800 ° C, preferably about 350 to 500 ° C. Thereafter, in step S4, the supply of the PET gas and the O ₂ gas is stopped, and only the N 2 gas is supplied to perform purging. Further, in step S5, the supply of N ₂ gas is stopped to stop all gases, and the processing chamber 內 is evacuated. Note Step S the 4 first and second supply pipes 5 a, 5 b of least for the one by the supply pipe Ri N ₂ gas also is introduced purged exhaust into the processing chamber 2 1. By performing the above steps S1 to S5, one pre-coating sequence to the mounting table 32 is completed. Thereafter, the cycle of steps S1 to S5 or steps S2 to S5 is repeated as many times as necessary. As a result, the segment films are stacked to form a precoat. The number of cycles is appropriately adjusted depending on the thickness of the thin film formed in one cycle.

Ri by the above process,载置base 3 2 is coated Ri by the T a ₂ 〇 ₅ film or Ranaru pre coat. Thereafter, while maintaining the temperature of the mounting table 32 by the heater 34, the inside of the processing chamber 21 is evacuated, the gate valve 26 is opened, and the transfer arm (not shown) is opened. Then, the wafer W is carried into the processing chamber 21. Next, the wafer W is mounted on the upper surface of the mounting table 32 (on the pre-coat) by the cooperation of the transfer arm and the lift bin 36, and the gate valve 26 is closed. Then, the process shifts to the film forming process (film forming process) on the wafer W.

In the film forming step, PET and O ₂ gas are supplied to the wafer W mounted on the mounting table 32 while evacuating the processing chamber 21. This ensures that, to form the T a ₂ 0 ₅ film of desired thickness on the wafer W. At this time, the processing conditions were the pre-coating described above. The same conditions as in step 3 of the treatment can be used.

According to such an embodiment, performing a film forming process on a wafer after performing a pre-coating process can reduce the concentration of metal contamination in a thin film formed on the wafer. Has the effect. Ri by the experiments, by using a table that has been pre-coat by performing a predetermined number of times pre-code Tosai cycle (sequence) of Fig. 7, T a ₂ 〇 the wafer

_Five films were formed, and the concentration of metal contamination in the thin film was measured.

Figure 8 is a graph showing the experimental results. 8, the horizontal axis indicates the number of repetitions of the pre-co. Over Tosai cycle (sequence), the vertical axis represents the number of atoms per unit area per Ri iron T a ₂ 0 ₅ film. “X” indicates the results when the target film thickness of the precoat is 90 nm and the number of repetitions of the precoat sequence is 4 and 7 times. “△” shows the results when the target film thickness of the precoat is approximately 21 O nm and the number of repetitions of the precoat sequence is 8, 16, and 32. “〇” shows the results when the target film thickness of the precoat is approximately 170 nm and the number of repetitions of the precoat sequence is 26 and 32.

For example, for the data indicated by “△”, when the above sequence is repeated eight times, the thickness of the precoat film formed by one sequence is approximately 26 nm (210 nm). nm / 8). When the above sequence is repeated 16 times, the thickness of the precoat film formed by one sequence is approximately 13 nm (21 O nm / 16). When the above sequence is repeated 32 times, the thickness of the precoat film formed by one sequence is approximately 6.5 nm (210 nm / 32). As is evident from the results in Fig. 8, the concentration of iron (contamination) incorporated into the thin film was reduced by increasing the number of precoating sequences, and the -There is a strong correlation with the number of data sequences. Although Fig. 8 shows the iron concentration, similar results can be obtained for aluminum and copper.

The design rules of semiconductor devices (the line width of the turn) are becoming stricter year by year, and the amount of metal contamination (metal contamination) that must be allowed must be reduced accordingly. . At present, the standard for metal contamination is 1. OE + 11 (atoms / cm ² ). Judging from this, the number of repetitions of the precoat sequence is preferably 13 or more. More preferably, more than 15 times. However, this standard for metal contamination is subject to change at the request of the user, and as shown in Fig. 8, when the number of repetitions of the pre-coating sequence is four or more, The effect is clearly confirmed.

As described above, the pre-coat requires a certain thickness in order to avoid a change in the thermal emissivity and to maintain a uniform film thickness between wafers (between planes). The thickness of the Ta ₂ O ₅ film is about 90 nm. Therefore, in order to complete the pre-coating process in the shortest time, the thickness of the segment film formed in each pre-coating sequence is set to a value obtained by dividing 90 nm by the number of repetitions. For example, if the number of repetitions is four, the thickness of the segment film is about 22.5 nm. If the number of repetitions is 15 times, the thickness of the segment film is about 6 nm. However, the thickness of the segment film formed in each pre-recording sequence is arbitrary. Can be set to

The following mechanism is considered as the reason why the amount of metal contamination in the film of the wafer is reduced by repeating the pre-coating sequence a plurality of times. That, T a ₂ 〇 ₅ film is deposited Ri by the thermal decomposition of PET. 0 ₂ gas introduced simultaneously Assistant Togasu der Ri, T a ₂ O ₅ film quality, although concerned such as the reaction rate does not come appear in the chemical equation of generating the T a 2 O ₅ film. This chemical reaction equation is expressed as follows. PET first decomposes as shown in equation (11).

_{_{_{2Ta (OC 2 H 5) 5}}} → Ta 2 0 5 + 5C2H4 + 5C 2 H 5 OH · · · (11) further above C ₂ H ₅ OH when pyrolysis to proceed cormorants good of formula (1 2) Decompose into

5C ₂ H ₅ OH → 5C ₂ H ₄ + 5H ₂ 0 .. (12)

Next, assuming that a metal chloride, for example, FeC 13, is present in the processing chamber 21, ethyl alcohol represented as an intermediate product in the above formula and formula (13) are obtained. Reacts to form ethoxylates.

FeCl ₃ + 3C ₂ H ₅ OH → Fe (OC ₂ H ₅ ) 3 + 3HCl − − (13) This ethoxylate is easily vaporized and exhausted depending on the processing temperature in the processing chamber 21. For this reason, during the pre-coating, the metal chloride that causes metal contamination during the subsequent film formation of the wafer can be reduced. Unlike the pre-coating of the TiN film, the metal chloride is not generated during the pre-coating of the Ta ₂ O 5 film, unlike the pre-coating of the TiN film. On the other hand, the inside of the processing chamber 21 is periodically cleaned with a cleaning gas containing halogen, for example, C 1 Ri by the F ₃ gas is cleanings. It is presumed that the metal chloride was generated during this cleaning.

Even though the metal ethoxylate is vaporized and exhausted, it is unavoidable that it is generated during the precoating and drifts in the processing chamber 21 or adheres to the inner wall of the processing chamber. Therefore, as shown in FIG. 7, in a single precoating sequence, following the above-described reaction in step S3, the by-product containing unreacted ethoxylate is purged with N _{2 in} step S4. To be discharged. Further, desirably, even in the step S5, even the staying portion of the N 2 purge is cut off, so that the amount of metal contamination can be further reduced. In steps S1 to S4, since the evacuation of the processing chamber 21 is continued, the step S5 may not be performed. The gas flow in step S 3 is N _2. Other inert gas is not limited to gas, may be filed in example A r.

After continuous processing of wafers, it may take some time before processing of the next lot starts. If this idle time is referred to as idling, when the processing is restarted after idling, the amount of methanol contamination in the film of the wafer may be large. This may be because alcohol and the like are diffused back into the processing chamber 21 from the exhaust system. That is, in the exhaust system of the processing chamber 21, a throttle valve for adjusting the pressure, a trap for capturing unreacted substances and by-products, and a vacuum pump are sequentially provided from the upstream side of the exhaust pipe 24. Will be installed. During idling, the inside of the processing chamber 21 is purged with an inert gas, for example, N ₂ gas. However, alcohol and the like in the by-products trapped in the trap may diffuse back into the processing chamber 21 and produce ethoxylated products represented by the above formula (13). There is.

Therefore, when the process is restarted after idling, if the above-described cycle pre-coating is performed, the amount of metal contamination in the wafer formed during the process can be reduced. Further, in this case, it is effective to repeatedly perform the purge and the vacuum exhaust according to the time table shown in FIG. In Figure 9,

“5a:”, “5b:”, and “5c:” have the same meaning as described in FIG. In the following steps S11 to S15, the evacuation of the processing chamber 21 is continued.

Step S 1 1 is a process for forming the T a ₂ O 5 film we row against the wafer just prior to entering the eye de-ring. Step S12 indicates a time zone during idling (it is fluid depending on the situation, for example, 360 seconds). Next, in a step S 13, preparations for starting the next lot process are started. Here, O ₂ gas and N ₂ gas are supplied into the processing chamber 21 to perform a first purge. Followed by feeding in the step S 1 4 even less N ₂ gas Ri good step S 1 3 in the processing chamber 2 in 1 second purge is carried out. Thereafter, evacuation is performed in step S15. This step S 1 3 ~ Step S 1 5 is repeated as necessary, i.e. a predetermined number of cycles purge is performed, deposition process line for subsequent next opening Tsu preparative wafer T a ₂ O 5 film Be done.

Note Step S 1 2 and Step S 1 in 4 the first and second supply pipes 5 a, 5 b of least for the one by Ri N ₂ gas supply pipe processing chamber even It is introduced into 21 and purged. In step S 13, the environment in the processing chamber 21 is prepared under the same conditions as in the film forming process on the wafer in step S 11 except for the PET gas. This also serves as conditioning (environmental adjustment) for approaching the environment in the processing chamber 21 during the subsequent film formation processing of the next lot wafer. The number of cycle purges shown in FIG. 9 is not so effective once, and at least three times.

An experiment was performed to confirm the effect of the cycle purge shown in Fig. 9. As a reference example, a Ta ₂ O 5 film is formed on the wafer before idling, that is, A 1, Fe and C in the thin film of the wafer after step S 11 are completed. The concentration of u was determined. As a comparative example, after the long-term idling state, that is, at the end of step S12, the same treatment was performed, and the concentration of the metal in the thin film of the wafer was similarly examined. As an example, after idling, the steps (cycle purging) of steps S13 to S15 shown in FIG. 9 were repeated five times (5 minutes during this time), and then the same processing was performed. Similarly, the concentration of the metal in the thin film of the wafer was examined.

FIG. 10 shows data showing the results of this experiment. According to this result, the amount of metal contamination in the embodiment substantially returns to the data before idling in any of A1, Fe, and Cu. It is presumed that, in addition to the ethoxylate formation described above, the following points may be acting as another factor. That is, the pressure in the processing chamber 21 in the process S13 in FIG. 9 is different from the pressure in the process S12 and the process S13 before and after the process. 8861

33 Largely different. Due to the sudden change in pressure and the exhaust that occurs at the same time, metal chloride, which is a source of metal contamination, is removed from the processing chamber.

2 The components in 1 are peeled off and exhausted. For this reason, in the subsequent film forming process, the amount of the impurity metal taken into the film decreases.

In the second embodiment, the above description illustrates a method of forming a tantalum oxide film using PET (the second processing gas is oxygen) as the first processing gas. But the second

The second embodiment is a film forming method using a metal alkoxide which is another organometallic source gas, for example, Ta (OC 2 H 5) ₅ ,

The _{_{S i (OC 2 H 5)}} 4 was used as the first process gas, respectively T a ₂ 0 ₅ film, TEOS - Ru can and this also applied to a method of forming a S i 〇 ₂ film . In these methods, as the second processing gas 0 _2, 0 _3, H ₂ 0 of which the oxygen-containing gas becomes available.

As described above, according to the first and second embodiments, for example, a metal or the like contained in a film formed on a substrate to be processed after performing a pre-coating process in a processing chamber. The total amount of impurities can be reduced.

That is, according to the first and second embodiments, in the first step of the pre-coating process, unreacted substances dissociated from the processing gas, existing in the processing chamber, or contained in the thin film. The entered by-products etc. are discharged from the processing chamber in the second step. For this reason, the purity of a film composition formed on the substrate to be processed in a later film formation step is improved. For example, the second embodiment is applied to a case where a tantalum oxide film is formed using PET and O ₂ gas as a processing gas: In this case, according to the embodiment, an oxygen gas as a reaction gas is used. By performing the second step of the pre-coating process, the carbon in the pre-coating / processing chamber can be removed. In the case where a tantalum oxide film is formed in a processing chamber that has been in a long-term idle state. According to the embodiment, the processing is performed by supplying an inert gas in the second step of the pre-coating processing. Metal compounds in the room can be removed.

On the other hand, according to the first embodiment, in the first step of the pre-coating treatment, unreacted halides dissociated from the processing gas or halides as by-products that have entered the film. Is generated. In a second step, these halides are reduced by, for example, NH ₃ gas, and the halides separated in this reduction reaction are discharged from the processing chamber in a gaseous state. For this reason, the risk of metal contamination of the film formed on the substrate to be processed in the subsequent film formation process is reduced.

For example, when forming a TiN film, NH 3 and TiC 14 can be used as processing gases. In this case, TiC1X, HC1 and the like generated in the first step can be removed from the processing chamber in the second step. As a result, the amount of metal chloride mixed into the TiN film obtained in the film forming process is reduced.

Claims

1. A film forming method for semiconductor processing for forming a film containing a metal element on a substrate to be processed mounted on a mounting table in an airtight processing chamber,

(a) a pre-coating step of covering the mounting table with a pre-coat before the substrate blue plate is loaded into the processing chamber; and

The first processing gas containing the raw material gas containing the metal element is supplied to the processing chamber while heating the mounting table and exhausting the processing chamber.

A first step of supplying a room and forming a segment film containing the metal element on the mounting table;

While heating the mounting table and exhausting the processing chamber, a second processing gas not containing a source gas containing a metal element is supplied into the processing chamber, and the segment generated in the first step is supplied to the processing chamber. A second step of removing by-products other than components that form a film from the processing chamber by exhaustion;

Having

Loading the substrate to be processed into the processing chamber and mounting the substrate on the mounting table; The first and second processing gases are supplied into the processing chamber while heating the mounting table and exhausting the processing chamber to form the main film containing the metal element on the substrate to be processed. Having steps and.

Is provided.

2. The method according to claim 1, wherein substantially the same processing temperature and processing pressure are used in the first and second steps, and the by-product sublimates at the processing temperature and processing pressure.

3. The method according to claim 1, wherein the first processing gas includes a compound of the metal element and the halogen element, and the second processing gas includes at least one of a nitrogen atom and a hydrogen atom.

4. The second process gas ammonia, N _2, The method according to claim 3, wherein also include one from the group consisting of H ₂ rather small is selected.

5. The method of claim 3, wherein said first processing gas comprises titanium tetrachloride, said second processing gas comprises ammonia, and said main film consists essentially of a titanium nitride film.

6. The method according to claim 3, wherein the first processing gas includes titanium tetrachloride and hydrogen, the second processing gas includes hydrogen, and the main film substantially consists of a titanium film.

7. In the second step, while stopping the first processing gas, supplying the second processing gas into the processing chamber, and forming an intermediate formed by decomposition or reaction of the first processing gas. 2. The method according to claim 1, wherein a by-product generated by a reaction between the gas and the second processing gas is removed by exhaust gas.

8. The method according to claim 1, wherein the first processing gas includes an alkoxide of the metal element, and the second processing gas includes an oxidizing gas.

9. The method of claim 8, wherein said first processing gas comprises pentaethoxy tantalum, and wherein said main film consists essentially of a tantalum oxide film.

10. The method according to claim 7, wherein said second step further comprises a purge period in which said first and second processing gases are stopped and said processing chamber is evacuated.

11. The method according to claim 10, wherein said second step comprises supplying an inert gas into said processing chamber during said purge period.

12. The first processing gas is a gas that generates alcohol by thermal decomposition, and the by-products are alcohol generated by the decomposition of the first processing gas and alcohol. 9. The method according to claim 8, which is produced by reacting a metal halide with a metal halide.

13 3. Between the pre-coating step and the film forming step,

An idling step of supplying an inert gas into the processing chamber while exhausting the processing chamber;

A first purge step of supplying a second processing gas into the processing chamber while exhausting the processing chamber;

A second purge step of supplying an inert gas into the processing chamber while exhausting the processing chamber;

2. The method according to claim 1, further comprising: repeating the first and second purge steps three or more times.

14. A cleaning step of supplying a cleaning gas containing a halogen element into the processing chamber to clean the processing chamber before the pre-coating step, further comprising: 13. The method according to claim 12, wherein the compound is derived from the halogen element.

15. A first processing gas containing the metal element and a first processing gas containing the metal element in the processing chamber to form a film containing the metal element on a substrate to be processed placed on a mounting table in an airtight processing chamber. A CVD method for forming a film containing the metal element on the substrate to be processed while supplying a second processing gas for assisting the decomposition of

The first and second processing gases are supplied into the processing chamber while heating the mounting table and exhausting the processing chamber. The second step of forming a segment film containing the metal element on the mounting table. Step 1 and

While stopping the first processing gas, heating the mounting table and exhausting the processing chamber, supplying the second processing gas into the processing chamber, and decomposing or reacting the first processing gas. A second step of reacting the intermediate produced by the above with the second processing gas to generate a by-product, and removing the by-product from the processing chamber by exhaustion;

Forming the precoat by stacking a plurality of segment films by repeating the first and second steps a plurality of times. When,

Wherein substantially the same processing temperature and processing pressure are used in the first and second steps, and the by-product sublimates at the processing temperature and processing pressure;

Supplying the first and second processing gases into the processing chamber while heating the mounting table and exhausting the processing chamber, and forming the main film containing the metal element on the substrate to be processed. Having and

Is provided.

16. The pre-coating step includes the first and second steps.

The method according to claim 15, wherein the method is repeated for at least 0 cycles.

17. The method according to claim 15, wherein the first processing gas includes a compound of the metal element and the halogen element, and the second processing gas includes at least one of a nitrogen atom and a hydrogen atom.

18. The method according to claim 15, wherein the first processing gas includes an alkoxide of the metal element, and the second processing gas includes an oxidizing gas.