CN117778991A - Film forming method and film forming device - Google Patents

Abstract

The present invention relates to the field of semiconductor device manufacturing technology, and more particularly, to a film forming method and a film forming apparatus. The invention provides a film forming method, which comprises the following steps: moving the wafer into the chamber, judging whether a specified film with a certain thickness exists in the chamber as a precoating layer, and if so, entering the next step; introducing chemical source gas, and depositing a buffer layer above the precoat; introducing a precursor, depositing a prescribed film above the buffer layer, and introducing a reducing gas to reduce the residual precursor; wherein the prescribed film is a Ti-containing metal film, and the precursor is an inorganic Ti-containing material. The invention can cover particles in the chamber by improving the process, controlling the temperature accurately and optimizing the time of entering the chamber, effectively control the diffusion and pollution of the particles in the chamber, and effectively avoid potential equipment problems while improving the quality of the film, thereby improving the production efficiency and the product quality.

Description

Film forming method and film forming device

Technical Field

The present invention relates to the field of semiconductor device manufacturing technology, and more particularly, to a film forming method and a film forming apparatus.

Background

As the development of microelectronics and deep submicron chip technology requires ever decreasing device and material dimensions, the aspect ratio in devices is ever increasing, and thus the thickness of the materials used is reduced to the order of a few nanometers. ALD (Atomic layer deposition ) is a method that can plate substances on a substrate surface layer by layer in the form of a monoatomic film, has excellent control over the composition and thickness of thin films compared with other deposition methods, and the prepared thin films have good conformality, high purity and uniformity, and are favored in the field of semiconductor material preparation.

In the manufacturing process of semiconductor devices, a metal film such as a TiN (titanium nitride) film is generally formed on a semiconductor wafer by an Atomic Layer Deposition (ALD) method or the like. Before the wafer is formed into a film, a pre-coating step is performed on the surface of the chamber to form a TiN film on the surface of the chamber. Through the precoating step, particles attached to the surface of the chamber can be effectively prevented from scattering to the wafer.

However, the TiN film covered on the surface of the chamber may be cracked due to the temperature decrease of the chamber or the like. Particles such as TiN molecules and Ti atoms that are not nitrided may be hidden in these cracks. During the process, these particles may fly to the wafer surface, resulting in problems such as excessive particle height on the wafer surface.

Currently, it takes a long time to solve the problems of metal contamination or particle excessive height of the existing TiN chamber, and the thermal atomic layer deposition (thermal ALD) chamber process without Remote Plasma Source (RPS) cleaning is costly.

Therefore, the prevention of wafer contamination by metals and particle excessive height becomes a critical issue to be studied. In the prior art, a method of coating the chamber wall is adopted, so that particles which are not adsorbed on the chamber wall in the chamber can be effectively prevented from splashing to the surface of a wafer, and the problems of metal pollution and overhigh particles are avoided. In addition, the method can also prolong the service cycle of the reaction cavity of the chamber.

Chinese patent No. CN109423625B discloses a film forming method which first deposits 12000 cycles (cycles) of TiN as a precoat. Subsequently, the temperature was reduced to 200 ℃. Then, siH4 is introduced to form a-Si on the TiN surface to cover the process kit surface in the chamber and the particles in the TiN cracks. The wafer is next moved into the chamber and a Cl-free TiSiN film is deposited using TDMAT (titanium tetradimethylamino), NH3, and SiH4 for at least 1 cycle.

The technical scheme has the following problems:

1) In the process of using TDMAT as a titanium source, since it is an organic metal compound containing carbon element, C element pollution may be introduced during deposition, and such pollution may affect the performance of TiSiN or TiN thin film;

2) The use of two Ti-containing precursors, tiCl4 and TDMAT, for deposition increases production costs;

3) TDMAT is a chlorine-free titanium source, belongs to an organic metal compound, has a relatively low decomposition temperature, needs to be cooled to 200 ℃ to deposit TiSiN or TiN, and can cause the aggravation of the cracking problem of the TiN film and the peeling of the TiN film in the cavity if the temperature is too fast or the temperature is controlled improperly, and has a larger influence on the service life of the heating disc;

4) During deposition, a thicker TiN film is deposited on the heated platen due to the inability of the wafer to move into the chamber in advance, which may affect subsequent processes and reduce the lifetime of the vacuum chuck.

In summary, the above technical solution has a plurality of problems to be solved. In order to improve the production efficiency and reduce the cost, the prior technical scheme needs to be improved and perfected.

Disclosure of Invention

The invention aims to provide a film forming method and a film forming device, which solve the problems of metal pollution and overhigh particles caused by splashing of particles in a semiconductor cavity to the surface of a wafer in the prior art.

In order to achieve the above object, the present invention provides a film forming method comprising the steps of:

moving the wafer into the chamber, judging whether a specified film with a certain thickness exists in the chamber as a precoating layer, and if so, entering the next step;

introducing chemical source gas, and depositing a buffer layer above the precoat;

introducing a precursor, depositing a prescribed film above the buffer layer, and introducing a reducing gas to reduce the residual precursor;

wherein the prescribed film is a Ti-containing metal film, and the precursor is an inorganic Ti-containing material.

In some embodiments, the determining whether a specified film of a certain thickness is present as a precoat layer in the chamber further comprises:

if no precoat is present, a specified film of a certain thickness is deposited as a precoat.

In some embodiments, the depositing a specified film of a certain thickness as a pre-coat layer further comprises the steps of:

introducing the precursor to enable the precursor to be adsorbed on the surface of the chamber;

introducing purge gas to purge redundant precursor in the cavity;

introducing a reaction gas to react with the precursor adsorbed on the surface of the chamber to generate a specified film;

and (3) introducing a purge gas to purge redundant reaction gas in the cavity.

In some embodiments, the depositing a buffer layer over the pre-coat layer further comprises the steps of:

introducing chemical source gas to form a buffer layer above the precoat layer;

and (3) introducing a purge gas to purge redundant chemical source gases in the cavity.

In some embodiments, the depositing a defined film over the buffer layer further comprises the steps of:

introducing the precursor to enable the precursor to be adsorbed on the surface of the buffer layer;

introducing purge gas to purge redundant precursor in the cavity;

introducing a reaction gas to react with the precursor adsorbed on the surface of the buffer layer to generate a specified film;

and (3) introducing a purge gas to purge redundant reaction gas in the cavity.

In some embodiments, the step of depositing a buffer layer over the pre-coat layer further comprises:

and (3) introducing a reducing gas to reduce the residual precursor.

In some embodiments, the reducing gas is H2.

In some embodiments, the purge gas comprises nitrogen and/or an inert gas.

In some embodiments, the reactant gas is NH3.

In some embodiments, the buffer layer is an amorphous silicon film and the chemical source gas is dichlorosilane.

In some embodiments, the depositing a specified film as a precoat layer to a thickness corresponds to a cycle period of at least 10000 cycles.

In some embodiments, the depositing a buffer layer over the precoat layer corresponds to a cycle period of at least 100 cycles.

In some embodiments, the precursor is introduced, a prescribed film is deposited over the buffer layer, and the residual precursor is reduced by introducing a reducing gas, with a corresponding cycle period of at least 10 cycles.

In some embodiments, the process temperature within the chamber is maintained at the same temperature range.

In order to achieve the above object, the present invention provides a film forming apparatus comprising:

a process chamber having a wafer carrier tray for loading wafers therein;

a first gas supply for introducing a chemical source gas into the process chamber;

a second gas supply for introducing a precursor into the process chamber;

a third gas supply part for introducing a reducing gas into the process chamber;

a fourth gas supply part for introducing a reaction gas into the process chamber;

a fifth gas supply portion for introducing a purge gas into the process chamber;

and a controller configured to output control signals to control the process chamber, the first gas supply unit, the second gas supply unit, the third gas supply unit, the fourth gas supply unit, and the fifth gas supply unit, so as to implement the film forming method according to any one of the above-described methods.

The invention provides a film forming method and a film forming device, which are suitable for a chamber with metal pollution problem and a chamber with poor particles, can cover the particles in the chamber by improving the process, controlling the accurate temperature and optimizing the time for entering the chamber of a wafer, effectively control the diffusion and pollution of the particles in the chamber, and effectively avoid the potential equipment problem while improving the quality of a film, thereby improving the production efficiency and the product quality.

Drawings

The above and other features, properties and advantages of the present invention will become more apparent from the following description of the embodiments with reference to the accompanying drawings, in which like reference numerals refer to like features throughout,

wherein:

FIG. 1 is a step diagram of a film forming method according to an embodiment of the present invention;

FIG. 2 discloses a schematic view of a chamber coating with pre-coat already present in accordance with an embodiment of the invention;

FIG. 3 discloses a schematic view of a chamber coating without a pre-coat layer according to an embodiment of the invention;

FIG. 4 is a schematic diagram showing a film forming process according to an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.

Fig. 1 discloses a step diagram of a film forming method according to an embodiment of the present invention, as shown in fig. 1, the film forming method according to the present invention includes the following steps:

step S1, moving a wafer into a chamber, judging whether a specified film with a certain thickness exists in the chamber as a precoating layer, and if so, entering step S2;

s2, introducing chemical source gas, and depositing a buffer layer above the precoat;

and S3, introducing a precursor, depositing a specified film above the buffer layer, and introducing a reducing gas to reduce the residual precursor so as to reduce the chlorine content.

In this embodiment, the prescribed film is a Ti-containing metal film, and the precursor is an inorganic Ti-containing material.

It should be noted that the choice and use of the precursor needs to be determined according to specific preparation conditions and material requirements. Different precursors have different chemical properties and reactivity, so that in practical application, the precursors need to be selected and optimized according to practical situations.

Further, the Ti-containing metal film may be a TiN film, and the precursor may be TiCl4.

These steps will be described in detail below. It is understood that within the scope of the present invention, the above-described technical features of the present invention and technical features specifically described below (e.g., in the examples) may be combined with each other and associated with each other, thereby constituting a preferred technical solution.

Step S1, a wafer is moved into a chamber, whether a specified film with a certain thickness exists in the chamber as a precoating layer is judged, and if the specified film exists in the chamber, the step S2 is carried out.

In the prior art, the metal contamination problem on the surface of the heating plate is solved by using a coating, so that a film is deposited on the surface of the heating plate before the wafer is moved into the chamber. However, depositing thicker TiN films on the hotplate may adversely affect subsequent processing and reduce the useful life of the vacuum chuck.

In this embodiment, since the ceramic material used for the heating plate does not cause metal contamination, the wafer can be moved into the chamber before the TiN precoating, and the wafer is used to prevent the film from growing on the surface of the heating plate as much as possible. Therefore, the heating plate and the vacuum chuck on the heating plate can be effectively protected, the influence on the subsequent process is avoided, and the smooth proceeding of the process is ensured.

Fig. 2 discloses a schematic diagram of a chamber coating in which a pre-coating layer is already present, and if a TiN film with a certain thickness is present on the surface of the chamber, as shown in fig. 2, step S2 is entered to start depositing a buffer layer.

FIG. 3 discloses a schematic view of a chamber coating without a pre-coating layer according to an embodiment of the present invention, as shown in FIG. 3, if the pre-coating layer is not present, a prescribed film of a certain thickness is deposited as the pre-coating layer on the surface of the chamber.

The method for depositing a prescribed film with a certain thickness as a precoating layer further comprises the following steps:

step S11, introducing a precursor to enable the precursor to be adsorbed on the surface of the chamber;

step S12, introducing purge gas to purge redundant precursors in the cavity;

step S13, introducing a reaction gas, and reacting with the precursor adsorbed on the surface of the chamber to generate a specified film;

and S14, introducing a purge gas to purge redundant reaction gas in the cavity.

In this example, the precursor was TiCl4, the prescribed film was TiN film, and the reactant gas was NH3.

The purge gas includes nitrogen, which is a colorless, odorless, nontoxic gas, which is relatively stable in chemical properties, and/or an inert gas, which is also a common purge gas. It is a chemically very inert gas such as argon, helium, etc.

In this embodiment, the purge gas is Ar.

This step is not required if a TiN film of sufficient thickness is already present in the chamber.

Fig. 4 discloses a process schematic of a film forming method according to an embodiment of the present invention, as shown in fig. 4, in the present embodiment, in the step S1, a predetermined thin film with a certain thickness is deposited as a precoat layer, and the corresponding cycle period is at least 10000 cycles.

And S2, introducing chemical source gas, and depositing a buffer layer above the precoat layer.

Further, the depositing a buffer layer over the pre-coat layer further comprises the steps of:

s21, introducing chemical source gas to form a buffer layer above the precoat layer;

and S22, introducing purge gas to purge redundant chemical source gas in the cavity.

In this embodiment, the buffer layer is an amorphous silicon (a-Si) film, the chemical source gas is Dichlorosilane (DCS) or silane, the purge gas is Ar, and the pre-coating layer is a TiN film.

Dichlorosilane (DCS) or silane is used as a chemical source gas to provide elemental silicon that forms a-Si (amorphous silicon).

Dichlorosilane, also known as dichlorosilane, is a colorless, toxic gas. Dichlorosilane has applications in many chemical reactions, for example, in semiconductor manufacturing processes, as a silicon source gas.

Silane, a generic term for a series of compounds, includes monosilane (SiH 4), disilane (Si 2H 6), and some higher silicon hydride compounds. Silane has applications in many chemical reactions, for example, as a silicon source gas in semiconductor manufacturing processes.

Whether dichlorosilane or silane, are important chemical source gases. They play an important role in the chemical reaction process.

Further, the step S22 further includes:

and (3) introducing a reducing gas to reduce the residual precursor, so as to reduce the chlorine content.

In this embodiment, the reducing gas is H2, the precursor is TiCl4, and the reducing gas H2 is introduced to reduce the residual precursor TiCl4, thereby reducing the chlorine content.

As shown in fig. 4, in this embodiment, the step S2 is to deposit a buffer layer over the precoat layer, and the corresponding cycle period is at least 100 cycles.

In this embodiment, the a-Si layer serves as a buffer layer capable of effectively covering cracks and particles, preventing them from scattering toward the wafer or the heating plate surface. In addition, by using the a-Si layer as a buffer layer, the size of TiN grains grown in the subsequent step S3 is reduced, thereby extending the time for exfoliation to occur.

Further, as a preferred embodiment, the present invention can produce a-Si by reacting DCS with TiN, and then H2 is introduced to eliminate Cl. The method does not need to additionally add an SiH4 gas pipeline, thereby being more suitable for the existing semiconductor machine.

And S3, introducing a precursor, depositing a specified film above the buffer layer, and introducing a reducing gas to reduce the residual precursor so as to reduce the chlorine content.

Further, the precursor is introduced to deposit a prescribed film on the buffer layer, and the method further comprises the following steps:

step S31, introducing a precursor to enable the precursor to be adsorbed on the surface of the buffer layer;

step S32, introducing purge gas to purge redundant precursors in the cavity;

step S33, introducing a reaction gas, and reacting with the precursor adsorbed on the surface of the buffer layer to generate a specified film;

and step S34, introducing a purge gas to purge redundant reaction gas in the cavity.

In this example, the precursor was TiCl4, the prescribed film was a TiN film, the reaction gas was NH3, the purge gas was Ar, and the buffer layer was an amorphous silicon (a-Si) film.

In depositing a low Cl-content TiN layer, tiCl4 is used instead of TDMAT as Ti source while Cl element is removed by H2.

A great advantage of the present invention over the prior art is that TDMAT is not required. This not only reduces the cost, but also avoids contamination of the chamber by the element C in TDMAT.

Furthermore, in the film forming method provided by the invention, the process temperature in the chamber is kept in the same temperature range. In this example, the temperature range is 450 ℃.

In the prior art, TDMAT is generally used as Ti source. However, ALD reactions require the precursor (TDMAT) to be stably adsorbed on the wafer surface. If a high temperature of 450 ℃ is used, TDMAT will decompose before adsorbing to the wafer surface, resulting in an inability to adsorb properly. Therefore, tiN can be deposited only at a relatively low temperature of around 200 ℃.

However, the present invention uses TiCl4 as a titanium source (precursor), which makes TiN deposition at 450℃possible. Furthermore, when depositing low Cl TiN layers, maintaining a temperature of 450 ℃ eliminates the need for cooling during the entire process, which helps to avoid the risk of TiN cracking and reduced service life of the heating plate.

In this embodiment, the reducing gas is H2.

H2 can reduce TiCl4 through the reactions of the formulas (1) and (2) to remove Cl, thereby obtaining the TiN film with low Cl content and high continuity.

2TiCl4+H2→2(TiCl3)++2HCl (1)

TiCl4+H2→(TiCl2)+++2HCl (2)

In this embodiment, as shown in fig. 4, in the step S3, the precursor is introduced, a predetermined thin film is deposited over the buffer layer, and the residual precursor is reduced by introducing a reducing gas to reduce the chlorine content, and the corresponding cycle period is at least 10 cycles.

While, for purposes of simplicity of explanation, the methodologies are shown and described as a series of acts, it is to be understood and appreciated that the methodologies are not limited by the order of acts, as some acts may, in accordance with one or more embodiments, occur in different orders and/or concurrently with other acts from that shown and described herein or not shown and described herein, as would be understood and appreciated by those skilled in the art.

The invention also provides a film forming device, which at least comprises a process chamber, a first gas supply part, a second gas supply part, a third gas supply part, a fourth gas supply part, a fifth gas supply part and a controller:

a process chamber having a wafer carrier tray for loading wafers therein;

a first gas supply for introducing a chemical source gas into the process chamber;

a second gas supply for introducing a precursor into the process chamber;

a third gas supply part for introducing a reducing gas into the process chamber;

a fourth gas supply part for introducing a reaction gas into the process chamber;

a fifth gas supply portion for introducing a purge gas into the process chamber;

and a controller outputting control signals to control the process chamber, the first gas supply unit, the second gas supply unit, the third gas supply unit, the fourth gas supply unit, and the fifth gas supply unit, so as to implement the film forming method.

The first gas supply portion, the second gas supply portion, the third gas supply portion, the fourth gas supply portion, and the fifth gas supply portion may be independent or may be connected to each other.

If they are independent, each supply will have an independent inlet, and if they are interconnected, they may be interconnected by pipes or connectors to form a gas supply system.

The film forming method and the film forming device provided by the invention are suitable for the chamber with metal pollution problem and the chamber with poor particles, and the particles on the inner wall of the chamber are covered by improving the process, controlling the accurate temperature and optimizing the time of entering the chamber, so that the diffusion and pollution of the particles in the chamber are effectively controlled, the quality of a film is improved, and meanwhile, the potential equipment problem is effectively avoided, thereby improving the production efficiency and the product quality.

The film forming method and the film forming device provided by the invention have the following beneficial effects:

1) On the basis of the existing semiconductor chamber, only one path of reducing gas (H2) is added, so that the improvement technology not only reduces the complexity and cost of equipment, but also improves the convenience of operation;

2) The TDMAT is not needed, so that the problem that the chamber is polluted by C is avoided, the whole process is kept at 450 ℃, the quality and stability of the film are guaranteed by the temperature control, the problem of TiN film cracks possibly generated in the heating plate heating and cooling process is effectively avoided, and the service life of the heating plate is prolonged;

3) The wafer is moved into the chamber before the precoating, further avoiding the influence of the TiN film on the service life of the heating plate and the vacuum chuck.

As used in this application and in the claims, the terms "a," "an," "the," and/or "the" are not specific to the singular, but may include the plural, unless the context clearly dictates otherwise. In general, the terms "comprises" and "comprising" merely indicate that the steps and elements are explicitly identified, and they do not constitute an exclusive list, as other steps or elements may be included in a method or apparatus.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more, unless otherwise clearly defined.

The embodiments described above are intended to provide those skilled in the art with a full range of modifications and variations to the embodiments described above without departing from the inventive concept thereof, and therefore the scope of the invention is not limited by the embodiments described above, but is to be accorded the broadest scope consistent with the innovative features recited in the claims.

Claims (15)

1. A film forming method comprising the steps of:

moving the wafer into the chamber, judging whether a specified film with a certain thickness exists in the chamber as a precoating layer, and if so, entering the next step;

introducing chemical source gas, and depositing a buffer layer above the precoat;

introducing a precursor, depositing a prescribed film above the buffer layer, and introducing a reducing gas to reduce the residual precursor;

wherein the prescribed film is a Ti-containing metal film, and the precursor is an inorganic Ti-containing material.

2. The film forming method according to claim 1, wherein the step of determining whether a predetermined film having a certain thickness is present as a precoat layer in the chamber, further comprises:

if no precoat is present, a specified film of a certain thickness is deposited as a precoat.

3. The film forming method according to claim 2, wherein the depositing a prescribed film of a certain thickness as a precoat layer, further comprises the steps of:

introducing the precursor to enable the precursor to be adsorbed on the surface of the chamber;

introducing purge gas to purge redundant precursor in the cavity;

introducing a reaction gas to react with the precursor adsorbed on the surface of the chamber to generate a specified film;

and (3) introducing a purge gas to purge redundant reaction gas in the cavity.

4. The film forming method according to claim 1, wherein the depositing a buffer layer over the precoat layer further comprises the steps of:

introducing chemical source gas to form a buffer layer above the precoat layer;

and (3) introducing a purge gas to purge redundant chemical source gases in the cavity.

5. The film forming method according to claim 1, wherein the supplying of the precursor deposits a prescribed film over the buffer layer, further comprising the steps of:

introducing the precursor to enable the precursor to be adsorbed on the surface of the buffer layer;

introducing purge gas to purge redundant precursor in the cavity;

introducing a reaction gas to react with the precursor adsorbed on the surface of the buffer layer to generate a specified film;

and (3) introducing a purge gas to purge redundant reaction gas in the cavity.

6. A film forming method according to claim 1, 2 or 3, wherein the step of depositing a buffer layer over the precoat layer further comprises:

and (3) introducing a reducing gas to reduce the residual precursor.

7. The film forming method according to claim 1, wherein the reducing gas is H2.

8. The film forming method according to claim 3, 4 or 5, wherein the purge gas includes nitrogen and/or an inert gas.

9. The film forming method according to claim 3 or 5, wherein the reaction gas is NH3.

10. The method according to claim 1, wherein the buffer layer is an amorphous silicon thin film, and the chemical source gas is dichlorosilane or silane.

11. The method according to claim 2, wherein the prescribed film is deposited as a precoat layer in a certain thickness with a cycle period of at least 10000 cycles.

12. The film forming method according to claim 1, wherein the buffer layer is deposited over the precoat layer with a corresponding cycle period of at least 100 cycles.

13. The method according to claim 1, wherein the precursor is introduced to deposit a predetermined thin film over the buffer layer, and the residual precursor is reduced by introducing a reducing gas, with a cycle period of at least 10 cycles.

14. The film forming method according to claim 1, wherein the process temperature in the chamber is maintained in the same temperature range.

15. A film forming apparatus includes:

a process chamber having a wafer carrier tray for loading wafers therein;

a first gas supply for introducing a chemical source gas into the process chamber;

a second gas supply for introducing a precursor into the process chamber;

a third gas supply part for introducing a reducing gas into the process chamber;

a fourth gas supply part for introducing a reaction gas into the process chamber;

a fifth gas supply portion for introducing a purge gas into the process chamber;

a controller outputting control signals to control the process chamber, the first gas supply, the second gas supply, the third gas supply, the fourth gas supply, and the fifth gas supply to implement the film forming method according to any one of claims 1 to 14.