Method for reducing resistance of contact hole

Abstract

The invention provides a method for reducing contact hole resistance. A through hole in a device structure is prepared; manufacturing an adhesion layer located in the through hole and attached to the inner wall of the through hole; manufacturing a metal film which is positioned in the through hole and is attached to the adhesion layer; and metal tungsten is filled in the through hole. From the perspective of compressing high-resistance metal Ti and TiN and increasing low-resistance metal tungsten, a fluoride-free chemical is used for replacing WF6 to participate in the reaction of a W thin film to form the tungsten thin film, so that a TiN thin film is replaced and formed, the effect of increasing the volume of tungsten is achieved, and the resistance of the through hole is reduced.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, and in particular to a method for reducing contact hole resistance. Background Art

[0002] There are currently two ways to improve device performance: one is to optimize device performance; the other is to optimize parasitic capacitance and resistance to improve the RC delay of the wire. As the integrated circuit process technology node becomes smaller and smaller, reducing the through-hole resistance is particularly important for improving device performance.

[0003] At present, the through-hole metals are Ti, TiN, and W from the outside to the inside. Among them, Ti metal is used as an adhesion layer, and TiN is used as a barrier layer to prevent the reaction gas WF6 in the W process from corroding Ti metal. The resistivity of the innermost layer W is the lowest. Because high-resistance metals Ti and TiN occupy a lot of space, the through-hole resistance is relatively high. The main reasons why the industry has no way to reduce the amount of high-resistance metals are: first, because W and SiO2 are easy to peel off, Ti metal is needed as an adhesion layer. Second, the W process is obtained by the reaction of WF6 and B2H6 / H4Si / H2, and "volcano" defects will occur when WF6 is in direct contact with Ti. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a method for reducing contact hole resistance, so as to solve the problem in the prior art that high contact hole resistance leads to decreased device performance.

[0005] To achieve the above-mentioned object and other related objects, the present invention provides a method for reducing the resistance of a contact hole, which at least comprises:

[0006] Step 1: preparing a through hole in the device structure; making an adhesion layer located in the through hole and attached to the inner wall of the through hole;

[0007] Step 2: preparing a metal film located in the through hole and attached to the adhesion layer; the metal film is a tungsten film;

[0008] Step three: filling metal tungsten in the through hole.

[0009] Preferably, the adhesion layer in step 1 is a Ti layer, a TiN layer or a composite layer of a Ti layer and a TiN layer.

[0010] Preferably, in step one, the adhesion layer is produced by physical vapor deposition.

[0011] Preferably, in step 2, the metal film is obtained by reacting with fluorine-free chemicals.

[0012] Preferably, the fluorine-free chemical in step 2 is WCL5.

[0013] Preferably, in step 2, the tungsten film is formed by reacting WCl5 with hydrogen.

[0014] Preferably, in step three, a fluorine reaction is used to fill metal tungsten in the through hole.

[0015] Preferably, in step three, metallic tungsten is formed by reacting WF6 with B2H6 or SiH4.

[0016] Preferably, in step three, metallic tungsten is formed by reacting WF6 with H2.

[0017] Preferably, the formation of metal tungsten in step three is divided into two steps. The first step is to form a tungsten layer attached to the metal film by reacting WF6 with B2H6 or SiH4; the second step is to form a bulk tungsten by reacting WF6 with H2.

[0018] As described above, the method of reducing the contact hole resistance of the present invention has the following beneficial effects: the present invention uses fluorine-free chemicals to replace WF6 to participate in the reaction of the W film from the perspective of compressing high-resistance metals Ti and TiN and increasing low-resistance metal tungsten. Thereby, the formation of the TiN film can be avoided, the effect of increasing the volume of tungsten is achieved, and the through-hole resistance is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a top view schematic diagram of a contact hole formed after the through hole of the present invention is formed by forming an adhesion layer, a metal film and filling metal tungsten;

[0020] Figure 2 Shown is a flow chart of the method for reducing contact hole resistance of the present invention. DETAILED DESCRIPTION

[0021] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0022] See also Figure 1 to Figure 2 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0023] The present invention provides a method for reducing the resistance of a contact hole. Figure 2 As shown, Figure 2The flowchart of the method for reducing the contact hole resistance of the present invention is shown, and the method at least comprises the following steps:

[0024] Step 1: preparing a through hole in the device structure; making an adhesion layer located in the through hole and attached to the inner wall of the through hole;

[0025] Furthermore, in the present invention, the adhesion layer in step 1 of this embodiment is a Ti layer, a TiN layer, or a composite layer of a Ti layer and a TiN layer.

[0026] According to the present invention, in step 1 of this embodiment, the adhesion layer is produced by physical vapor deposition.

[0027] like Figure 1 As shown, Figure 1 The schematic diagram of the top view of the contact hole formed after the through hole of the present invention is made of the adhesion layer, the metal film and the metal tungsten filling, that is, the schematic diagram of the cross section. In step 1, the through hole in the device structure is first prepared; the through hole is a hollow hole structure connecting the upper and lower layers of the device; then the adhesion layer 01 located in the through hole and attached to the inner wall of the through hole is prepared; the adhesion layer in this embodiment is a Ti layer, a TiN layer or a composite layer of a Ti layer and a TiN layer. Furthermore, in this embodiment, the adhesion layer is prepared by physical vapor deposition.

[0028] Step 2: preparing a metal film located in the through hole and attached to the adhesion layer; the metal film is a tungsten film.

[0029] According to the present invention, in step 2 of this embodiment, the metal film is obtained by reacting with fluorine-free chemicals.

[0030] In the present invention, the fluorine-free chemical in step 2 of this embodiment is WCL5.

[0031] In the present invention, further, in step 2 of this embodiment, a tungsten film is formed by reacting WCL5 with hydrogen.

[0032] like Figure 1 As shown, in step 2, a metal film 02 located in the through hole and attached to the adhesion layer 01 is prepared; the metal film is a tungsten film, and the metal film is obtained by reacting a fluorine-free chemical. Preferably, the fluorine-free chemical is WCL5. Further, the tungsten film is formed by reacting WCL5 with hydrogen.

[0033] Step three: filling metal tungsten in the through hole.

[0034] Furthermore, in the present invention, in step three of this embodiment, a fluorine reaction is used to fill metal tungsten in the through hole.

[0035] The present invention further comprises that in step three of this embodiment, metallic tungsten is formed by reacting WF6 with B2H6 or SiH4.

[0036] The present invention further comprises that in step three of this embodiment, metallic tungsten is formed by reacting WF6 with H2.

[0037] The formation of metal tungsten in step three is divided into two steps. The first step is to form a tungsten layer attached to the metal film by reacting WF6 with B2H6 or SiH4; the second step is to form a bulk tungsten by reacting WF6 with H2.

[0038] like Figure 1 As shown, in step three, metal tungsten 03 is filled in the through hole. The present invention adopts a fluorine reaction to fill metal tungsten in the through hole. In some embodiments, metal tungsten is formed by reacting WF6 with B2H6 or SiH4. In some embodiments, metal tungsten can also be formed by reacting WF6 with H2. In this embodiment, metal tungsten is formed in two steps. The first step is to form a tungsten layer attached to the metal film 02 by reacting WF6 with B2H6 or SiH4; the second step is to form a bulk tungsten by reacting WF6 with H2. Figure 1 The tungsten layer and the bulk tungsten are not shown separately. The present invention fills the via hole with the tungsten layer formed in the first step and the bulk tungsten formed in the second step.

[0039] In summary, the present invention uses fluorine-free chemicals to replace WF6 to participate in the reaction of W film to form tungsten film, thereby replacing the formation of TiN film, from the perspective of compressing high-resistance metals Ti and TiN and increasing low-resistance metal tungsten, thereby increasing the volume of tungsten and reducing through-hole resistance. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0040] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for reducing contact hole resistance, characterized in that: At least: Step 1: preparing a through hole in the device structure; making an adhesion layer located in the through hole and attached to the inner wall of the through hole; Step 2: preparing a metal film located in the through hole and attached to the adhesion layer; the metal film is a tungsten film; Step three: filling metal tungsten in the through hole.

2. The method for reducing contact hole resistance according to claim 1, characterized in that: The adhesion layer in step 1 is a Ti layer, a TiN layer, or a composite layer of a Ti layer and a TiN layer.

3. The method for reducing contact hole resistance according to claim 1, characterized in that: In step one, the adhesion layer is produced by physical vapor deposition.

4. The method for reducing contact hole resistance according to claim 1, characterized in that: In step 2, the metal film is obtained by using fluorine-free chemicals for reaction.

5. The method for reducing contact hole resistance according to claim 4, characterized in that: The fluorine-free chemical in step 2 is WCL5.

6. The method for reducing contact hole resistance according to claim 5, characterized in that: In step 2, a tungsten film is formed by reacting WCl5 with hydrogen.

7. The method for reducing contact hole resistance according to claim 1, characterized in that: In step three, a fluorine reaction is used to fill metal tungsten in the through hole.

8. The method for reducing contact hole resistance according to claim 7, characterized in that: In step three, metallic tungsten is formed by reacting WF6 with B2H6 or SiH4.

9. The method for reducing contact hole resistance according to claim 7, characterized in that: In step three, metallic tungsten is formed by the reaction of WF6 and H2.

10. The method for reducing contact hole resistance according to claim 7, characterized in that: The formation of metal tungsten in step three is divided into two steps. The first step is to form a tungsten layer attached to the metal film by reacting WF6 with B2H6 or SiH4; the second step is to form a bulk tungsten by reacting WF6 with H2.

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