JPH09186234A - Manufacturing device and method of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a metal plug in a contact hole high in yield by a method wherein a contact layer is formed on the inner surface of a contact hole and an interlayer insulating film, a metal film is formed thereon and then partially removed from the periphery of a semiconductor substrate, and then the metal film and the contact layer are etched back. SOLUTION: A contact hole 13 is provided in an interlayer insulating film 12 facing an impurity diffusion layer 11, and a contact layer 14 of Ti/TiN is formed on all the surface of the interlayer insulating film 12 by sputtering, including the contact hole 13. Furthermore, a semiconductor substrate 10 where the impurity diffusion layer 11, the interlayer insulating film 12 and others are formed is thermally treated and then introduced into a CVD device, and a metal film of tungsten is formed on the contact layer 14 through a CVD method. The metal film 15 located on the periphery of the substrate is removed by a polishing means without causing damage to the semiconductor substrate 10. Thereafter, the metal film 15 and the contact layer 14 are successively etched back, whereby a tungsten plug 17 is formed inside the contact hole 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device and a manufacturing apparatus thereof, and more particularly, to a method of manufacturing a semiconductor device for preventing generation of dust due to peeling of a metal film at a peripheral portion of a semiconductor substrate during film formation. The present invention relates to the manufacturing apparatus.

[0002]

2. Description of the Related Art With the high integration and high performance of semiconductor devices, multilayer wiring has become an essential technique. As a method of forming this multi-layer wiring, S with a contact hole opened
A blanket metal method is known in which the entire surface of an iO ₂ insulating film (interlayer insulating film) is coated with a refractory metal film such as a tungsten film so as to fill a contact hole and then etched back to form a metal plug in the contact hole. .

According to this blanket metal method, Si
Since the adhesion between the O ₂ insulating film and the metal film is poor, T
The i / TiN layer (adhesion layer) is interposed to improve the adhesion.

The reason why the adhesion is improved by the Ti / TiN layer is as follows.

The Ti layer is formed in order to ensure electrical conductivity with respect to the Si diffusion layer (impurity diffusion layer) which is an element below the SiO ₂ insulating film. TiN on this Ti layer
A layer is formed, and this TiN layer becomes a barrier layer for WF ₆ (tungsten hexafluoride) used especially when forming a tungsten film thereon, especially for F. That is,
WF ₆ is reduced in SiH ₄ gas, the reduced F gas is exhausted, and tungsten becomes TiN as a tungsten film.
Deposit on the layer. Without this TiN layer, the reduced F gas would reach the Ti layer directly and then react with Ti to form titanium tetrafluoride and be exhausted. In other words, the previously formed Ti layer disappears at the same time as the tungsten film is deposited and becomes hollow, so that the tungsten film and the SiO ₂ insulating film come into direct contact with each other, resulting in poor adhesion as described above. turn into. That is, if the TiN layer is formed on the Ti layer, the TiN layer serves as a barrier layer for the lower layer,
Since the reaction between F and Ti is blocked and the Ti layer is not lost, the adhesion is improved.

[0006]

However, according to the above-mentioned conventional blanket metal method, the tungsten film wraps around to the peripheral portion of the semiconductor substrate on which the Ti / TiN layer is not formed due to the difference in film properties. It is formed into a film. For example, when tungsten is formed by another device after the adhesion layer is formed, the pressing position at the peripheral edge of the substrate changes, so that the tungsten film is formed in the portion where the adhesion layer is not formed. Therefore, in this portion, the tungsten film is formed directly on the SiO ₂ insulating film or on the substrate, and the tungsten film is peeled off to generate dust, and as a result, the dust is reattached to the semiconductor integrated circuit portion. Therefore, the yield is reduced, and even if the film is not redeposited, the film formation in the next step is affected and the reliability is significantly deteriorated.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and is a method of manufacturing a semiconductor device which is economical, has a high yield, and is highly reliable, using the blanket metal technology suitable for forming a multilayer wiring structure as it is. An object of the present invention is to provide a method and a manufacturing apparatus thereof.

[0008]

In order to achieve the above object, the present invention provides a step of forming an interlayer insulating film on a semiconductor substrate, a step of forming a contact hole in the interlayer insulating film, and an inner surface of the contact hole. And a step of forming an adhesion layer on the interlayer insulating film, a step of forming a metal film on the adhesion layer, and a step of etching back the metal film and the adhesion layer to form a metal plug in the contact hole. And a step of removing the metal film on the peripheral portion of the semiconductor substrate before the step of forming the metal plug.

Further, according to the present invention, a step of forming a SiO ₂ insulating film on a Si substrate having an impurity diffusion layer formed therein, a step of forming a contact hole in the SiO ₂ insulating film by etching, and an inner surface of the contact hole. And Si
A step of forming a Ti / TiN adhesion layer on the O ₂ insulating film,
Method of manufacturing a semiconductor device, comprising: forming a tungsten film on the Ti / TiN adhesion layer; and etching back the tungsten film and the Ti / TiN adhesion layer to form a tungsten plug in the contact hole. In the method of manufacturing a semiconductor device, the step of removing the tungsten film on the peripheral portion of the Si substrate is added before the step of forming the tungsten plug.

A preferred embodiment is characterized in that the tungsten film on the peripheral portion of the Si substrate is removed by polishing with a polishing cloth impregnated with hydrogen peroxide solution.

Further, the present invention is a method for manufacturing a semiconductor device, which comprises a chuck for holding a semiconductor substrate, a rotary shaft for rotating the chuck, and a polishing means for contacting a peripheral portion of the semiconductor substrate held by the chuck. I will provide a.

In a preferred embodiment, the polishing means is characterized in that a belt-shaped polishing cloth is brought into contact with and transferred to the peripheral edge of the semiconductor substrate.

Further, in another preferred embodiment,
The polishing means is characterized in that the polishing cloth placed and fixed on the stage is brought into contact with the peripheral portion of the semiconductor substrate and rotated.

Further, in another preferred embodiment,
The polishing means is configured by impregnating a polishing cloth with a hydrogen peroxide solution.

Further, in another preferred embodiment,
It is characterized by comprising a nozzle for supplying cleaning water to the semiconductor substrate.

[0016]

[Function] After forming the interlayer insulating film, the adhesion layer, and the metal film on the semiconductor substrate in this order, and before they are etched back to form the metal plug in the contact hole of the interlayer insulating film, they wrap around the periphery of the semiconductor substrate. By removing the easily peelable metal film in advance, dust is prevented from being generated in the subsequent steps.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of an essential part of a substrate, which sequentially shows a film forming process in a method for manufacturing a semiconductor device according to the present invention.

FIG. 2 is a flow chart of this film forming process.

According to the flow chart of FIG. 2, first, step S
In FIG. 1, as shown in FIG. 1A, an impurity diffusion layer 11 which is a part of an element is formed on a semiconductor substrate 10 made of Si by a thermal diffusion method or an ion implantation method. Next, on the Si substrate 10 on which the impurity diffusion layer 11 is formed in step 2, for example, by the CVD method, as shown in FIG.
As shown in FIG. 3, an interlayer insulating film 12 made of a SiO ₂ oxide film is formed. A contact hole 13 facing the impurity diffusion layer 11 is opened in the interlayer insulating film 12 by dry etching such as RIE (step S3). Next, FIG.
As shown in (c), the entire surface of the interlayer insulating film 12 including the contact hole 13 is sputtered by Ti /
The adhesion layer 14 made of a TiN layer is formed (step S
4). It should be noted that the sputtering for forming the adhesion layer was performed using Ti
And TiN are used in two steps by changing the reaction gas. Further, after heat treatment, this semiconductor substrate is set in a CVD apparatus, and a metal film 15 made of tungsten is formed on the adhesion layer 14 by a blanket CVD method (step S5).

In FIG. 3, the metal film 15 is formed in step S5.
FIG. 6 is a cross-sectional view of the peripheral edge portion 16 of the substrate 10 after forming the.
As shown in FIG. 3, in this step S5, due to the difference in the holding position of the substrate chuck between the sputtering apparatus for forming the adhesion layer and the CVD apparatus for forming the tungsten film (no film is formed at the holding position). The metal film 15 is formed so as to wrap around the peripheral portion 16 of the semiconductor substrate 10 without the adhesion layer 14. The metal film 15a attached to the peripheral portion 16 is unnecessary as a wiring, and is peeled off as a dust source as described above.

Therefore, in the present invention, returning to FIG.
In step S6, the metal film 15a on the substrate peripheral portion 16 is removed by the polishing means without damaging the semiconductor substrate 10 as described later.

FIG. 4 is a sectional view showing a state where the metal film 15a on the peripheral portion 16 of the substrate is removed in this way. After removing the unnecessary metal film 15a, the metal film 15 and the adhesion layer 14 are sequentially etched back to form a plug 17 made of tungsten in the contact hole 13 as shown in FIG. (FIG. 2 step S7). At this time, since there is no unnecessary tungsten film on the substrate, dust is not generated due to peeling of the film, redeposition on the substrate does not occur, and a stable wiring structure with excellent quality can be obtained. Further, it does not adversely affect the film formation in the next step.

By following the manufacturing process as described above, the metal film 15 is not peeled off and becomes a dust source, and the yield is improved.

In the above embodiment, the blanket metal metal film 15 is a tungsten film, but a tungsten alloy or other refractory metal having the same function may be used.

FIG. 5 is an explanatory view showing an example of implementation of the polishing means constituting the semiconductor device manufacturing apparatus according to the present invention.

In this example, the polishing means 18 has a structure in which the belt-shaped polishing cloth 19 is transferred in the direction of arrow A by the rotating roller 20.

On the other hand, the semiconductor substrate 10 has a vacuum chuck 2
The chuck 21 is held by No. 1 and is directly connected to the rotary shaft 22 to rotate in the arrow B direction.

The polishing means 18 has a structure capable of advancing and retreating as a whole so that the polishing cloth 19 can be brought into and out of contact with the peripheral portion 16 of the semiconductor substrate 10 (arrow E).

Further, in the transfer path of the polishing means 18, there is provided a chemical liquid supply device 23 for dropping a chemical liquid consisting of hydrogen peroxide solution onto the polishing cloth 19 and impregnating it. This hydrogen peroxide solution is for dissolving the tungsten film, which is a blanket metal.

On the other hand, above the semiconductor substrate 10 on which the adhesion layer 14 and the metal film 15 are formed, a water injection nozzle 24 for cleaning the substrate during polishing is provided. The water can wash away the chemical solution scattered during polishing and the removed metal film pieces from the substrate. According to the polishing means 18 described above, the polishing cloth 19 is moved forward to bring the polishing cloth 19 into contact with the peripheral edge portion 16 of the semiconductor substrate 10 from the state shown in FIG.
By the state shown in (b), by rotating the semiconductor substrate 10 and moving the polishing pad 19, only the metal film 15a wrapping around the peripheral portion 16 of the semiconductor substrate 10 without the adhesion layer 14 is efficiently removed. be able to. Further, as described above, the semiconductor substrate 10 can be cleaned by pouring water from the nozzle 24.

FIG. 6 is an explanatory view showing another example of the polishing means 18 according to the present invention.

In this example, the polishing means 18 is a chemical mechanical polishing apparatus (CMP) having a structure in which a disk-shaped polishing cloth 19 is placed and fixed on a stage 26 directly connected to a rotary shaft 25. I decided.

On the other hand, the semiconductor substrate 10 has a vacuum chuck 2
The chuck 27 is grasped by 7, and has a structure in which the chuck 27 is directly connected to the rotating shaft 28 to rotate.

The stage 26 and the vacuum chuck 27 are structured to be movable in the vertical direction so that the polishing cloth 19 can be brought into contact with and separated from the peripheral portion 16 of the semiconductor substrate 10. Further, above the polishing cloth 19, as in the embodiment of FIG. 5, a chemical solution supply device 23 is provided for dropping a chemical solution containing hydrogen peroxide solution onto the polishing cloth 19 and impregnating the chemical solution.

According to the polishing means 18, the vacuum chuck 27 and the lower stage 26 are brought close to each other to bring the polishing cloth 19 into contact with the peripheral edge portion 16 of the semiconductor substrate 10 as shown in FIG. 6B. The rotation of the semiconductor substrate 10 in the direction of arrow C and the rotation of the polishing cloth 19 in the direction of arrow D cause the adhesion layer 1 to rotate.
It is possible to efficiently remove only the metal film 15a that has wrapped around the peripheral portion 16 of the semiconductor substrate 10 where there are no four.

The polishing means 18 of the above two embodiments is
Although both the semiconductor substrate 10 and the polishing cloth 19 are moved, it is also possible to move either one.

Further, the chemicals of the two examples are hydrogen peroxide solutions, but this is for dissolving the blanket metal tungsten, and other chemicals may be used. When a blanket metal other than tungsten is used, it is not limited to hydrogen peroxide solution as long as it can dissolve the metal.

Further, instead of the polishing cloth 19, a polishing sheet made of another material can be used.

[0040]

As described above, in the present invention, since the metal film on the peripheral portion of the semiconductor substrate 10 is removed before the blanket metal is etched back, the metal film is peeled off and becomes a dust source. It is possible to provide an economical semiconductor device manufacturing method and device having a high yield and reliability, which utilizes the blanket metal technology suitable for forming a multilayer wiring structure as it is. In addition, since there is no unnecessary metal film on the substrate during the etch-back process and subsequent processes, dust is not generated and re-adhesion does not occur on the substrate, and a stable wiring structure with excellent quality is obtained. In addition, it does not adversely affect the film formation in the next step.

[Brief description of the drawings]

1A to 1C are cross-sectional views sequentially showing a film forming process in a method for manufacturing a semiconductor device according to the present invention.

FIG. 2 is a flow chart related to steps of a method for manufacturing a semiconductor device according to the present invention.

FIG. 3 is a sectional view of a peripheral portion of a substrate before a metal film removing step according to the present invention.

FIG. 4 is a cross-sectional view of the peripheral portion of the substrate after the metal film removing step according to the present invention.

FIG. 5 is an explanatory view showing an example of an apparatus for carrying out the method for manufacturing a semiconductor device according to the present invention.

FIG. 6 is an explanatory view showing another example of an apparatus for carrying out the method for manufacturing a semiconductor device according to the present invention.

[Explanation of reference numerals] 10: semiconductor substrate, 11: impurity diffusion layer, 12: interlayer insulating film, 13: contact hole, 14: adhesion layer, 15:
Metal film, 16: peripheral portion, 14: plug, 18: polishing means.

Claims (8)

[Claims] 1. A step of forming an interlayer insulating film on a semiconductor substrate, a step of forming a contact hole in the interlayer insulating film, a step of forming an adhesion layer on the inner surface of the contact hole and the interlayer insulating film, A method of manufacturing a semiconductor device, comprising: forming a metal film on an adhesion layer; and etching back the metal film and the adhesion layer to form a metal plug in the contact hole. A method of manufacturing a semiconductor device, wherein a step of removing the metal film on the peripheral portion of the semiconductor substrate is added before the step of performing. 2. A step of forming a SiO ₂ insulating film on a Si substrate on which an impurity diffusion layer is formed, a step of forming a contact hole in the SiO ₂ insulating film by etching, an inner surface of the contact hole and a SiO ₂ insulating film. T on the membrane
forming an i / TiN adhesion layer, forming a tungsten film on the Ti / TiN adhesion layer, and etching back the tungsten film and the Ti / TiN adhesion layer to form a tungsten plug in the contact hole. A method of manufacturing a semiconductor device, which comprises a step of forming the semiconductor device, wherein a step of removing the tungsten film on the peripheral portion of the Si substrate is added before the step of forming the tungsten plug. 3. The method of manufacturing a semiconductor device according to claim 2, wherein the tungsten film on the peripheral portion of the Si substrate is removed by polishing with a polishing cloth impregnated with hydrogen peroxide solution. 4. A semiconductor device manufacturing method comprising: a chuck for holding a semiconductor substrate; a rotating shaft for rotating the chuck; and a polishing means for abutting a peripheral portion of the semiconductor substrate held by the chuck. apparatus. 5. The apparatus for manufacturing a semiconductor device according to claim 4, wherein the polishing means has a structure in which a belt-shaped polishing cloth is brought into contact with and transferred to the peripheral edge of the semiconductor substrate. 6. The semiconductor device according to claim 4, wherein the polishing means has a structure in which a polishing cloth mounted and fixed on a stage is brought into contact with a peripheral portion of a semiconductor substrate and rotated. Manufacturing equipment. 7. The apparatus for manufacturing a semiconductor device according to claim 4, wherein the polishing means is configured by impregnating a polishing cloth with a hydrogen peroxide solution. 8. The apparatus for manufacturing a semiconductor device according to claim 4, further comprising a nozzle for supplying cleaning water to the semiconductor substrate.