JPH1167686A - Manufacture of semiconductor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacture method which can inexpensively manufacture a semiconductor element having an adhered layer, where contact resistance does not increase or a diffusion layer is not damaged, even if high temperature heat treatment is executed in a short time. SOLUTION: A titanium nitride layer constituting the adhered layer is set to be a stack structure of first to third titanium nitride layers 104-106, and a second film forming condition used for forming the second titanium nitride layer 105 is made different from a first film-forming condition used for forming the first and third titanium nitride layers 104 and 106. Thus, the grain of the second titanium nitride layer 105 is made smaller than the grain of the first (third) titanium nitride layer 104. Since the titanium nitride layer, where the grains discontinuously grow, is formed only by temporarily changing the film forming condition, the semiconductor element having such a characteristic can inexpensively be manufactured in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a semiconductor device using a CVD (Chemical Vapor Deposition) method for forming a wiring (for example, a bit line).

[0002]

2. Description of the Related Art At present, polysilicon is widely used for forming bit lines. However, if bit lines are formed using tungsten (W), contact resistance and wiring resistance are reduced, so that high-speed operation is performed. A semiconductor device that operates in a short time can be manufactured. Also, if W is used, N
Since it becomes possible to connect the region doped with P-type and the region doped with P-type, formation of a bit line using W has attracted attention.

When a bit line is formed by W,
Since it is necessary to fill W in the contact hole, C
The VD method is used. However, since W has poor adhesion to an oxide film, when a bit line is formed by W, an adhesion layer is formed first, and then W is deposited.

As a method of forming the adhesion layer, Ti (titanium)
There is known a method in which a film and a TiN (titanium nitride) film are formed by a sputtering method, and thereafter, a lamp is heated in an atmosphere of N ₂ and NH ₃ . In addition, since the aspect ratio of a contact hole tends to increase in recent years as a result of miniaturization, an adhesion layer made of a Ti film and a TiN film with good coverage is provided on the inner surface of the contact hole having a large aspect ratio using a CVD method. Forming techniques have also been developed.

When a semiconductor element is manufactured, a heat treatment at a temperature of about 800.degree. C. may be required after forming a wiring to form a capacitor and the like. When such a high-temperature heat treatment is performed, the wiring metal is diffused to the Si side or the Si is diffused to the wiring metal side in the adhesion layer, so that the contact resistance increases,
There has been a phenomenon that the diffusion layer is destroyed.

As a technique for preventing the occurrence of such a phenomenon, Japanese Patent No. 2541657 discloses the following technique. In this technique, a reactive sputtering is first performed on a structure on which a Ti layer is formed, for about 50 minutes.
A nm thick TiN layer is deposited. Next, an interface layer is formed by oxidation of the surface layer of the TiN layer, and a TiN layer having a thickness of about 50 nm is deposited on the interface layer by reactive sputtering. Then, a wiring metal (Al) is deposited on the adhesion layer formed by such a procedure, in which the grain boundaries are discontinuous in the interface layer.

[0007]

The adhesion layer formed by the technique described in the above-mentioned patent publication does not have a continuous grain boundary, so that diffusion along the grain boundary hardly occurs. That is, the semiconductor element having the adhesion layer formed by the above-described procedure is less likely to cause an increase in contact resistance and breakage of the diffusion layer even when processed at a high temperature.

However, according to the technique described in the above-mentioned patent publication, a sample on which a TiN layer is formed is heat-treated while flowing a nitrogen gas in a reaction tube configured to allow a small amount of oxygen to penetrate, so that an interface layer is formed. Formation was taking place.
For this reason, there is a problem that the time required for forming the adhesion layer is long.

It is an object of the present invention to provide a method for manufacturing a semiconductor device which does not cause an increase in contact resistance or breakage of a diffusion layer even when high-temperature heat treatment is performed, in a short time and at low cost. It is another object of the present invention to provide a manufacturing method capable of manufacturing a semiconductor device having a fine contact hole.

[0010]

According to a first method of manufacturing a semiconductor device of the present invention, (a) a titanium layer having a silicide portion in contact with a diffusion layer is formed on a semiconductor device substrate having a contact hole. Forming titanium layer and (b)
On the titanium layer formed by this titanium layer forming step,
A first titanium nitride layer forming step of forming a first titanium nitride layer by a chemical vapor deposition method using a first film forming condition;
(C) On the first titanium nitride layer formed in the first titanium nitride layer forming step, a second titanium nitride layer different from the first film forming condition is formed.
A second titanium nitride layer forming step of forming a second titanium nitride layer having smaller grains than the first titanium nitride layer by a chemical vapor deposition method using film forming conditions; and (d) the second titanium nitride layer A third titanium nitride layer forming step of forming a third titanium nitride layer on the second titanium nitride layer formed by the layer forming step by a chemical vapor deposition method using the first film formation condition; A wiring metal layer forming step of forming a wiring metal layer on the third titanium nitride layer formed in the third titanium nitride layer forming step is used.

That is, in the first method of manufacturing a semiconductor device, the titanium nitride layer forming the adhesion layer is formed by the first to third steps.
And the second film forming condition used for forming the second titanium nitride layer is different from the first film forming condition used for forming the first and third titanium nitride layers. This ensures that the grains of the second titanium nitride layer are smaller than the grains of the first (and third) titanium nitride layer. According to this manufacturing method, a titanium nitride layer in which grains are grown discontinuously can be formed only by temporarily changing the film forming conditions. A semiconductor element having an adhesive layer that does not cause destruction can be manufactured in a short time and at low cost.

The first to third titanium nitride film forming processes
The process, together, TiCl_Four, NH_Three, N _TwoChemistry using gas
A process for forming a titanium nitride film by vapor phase epitaxy
If, for example, TiCl_FourThe conditions except for the gas flow rate are the first film formation
Same as the condition of TiCl_FourGas flow rate is the first
If the second film forming condition smaller than the flow rate of the film condition is used, the second
The grains of the second titanium nitride layer are the first (and third)
Make it smaller than the grain of the titanium nitride layer.
Can be.

According to the second method of manufacturing a semiconductor device of the present invention, (a) a titanium layer forming step of forming a titanium layer in which a portion in contact with a diffusion layer is silicided on a semiconductor device substrate having a contact hole formed therein; (B) forming a first titanium nitride layer on the titanium layer formed by the titanium layer forming step by a chemical vapor deposition method using a first film forming condition; (C) a plasma treatment of the first titanium nitride layer formed in the first titanium nitride layer forming step, thereby modifying a surface layer of the first titanium nitride film; A second titanium nitride layer forming a second titanium nitride layer by a chemical vapor deposition method using a first film forming condition on the first titanium nitride layer whose surface layer has been modified by the quality process; (E) Formation of this second titanium nitride layer A second titanium nitride layer formed by degree, and the wiring metal layer forming step of forming a metal layer for wiring is used.

That is, according to the second method for manufacturing a semiconductor device, when forming the titanium nitride layer constituting the adhesion layer, first, the first titanium nitride layer is formed, and then the first titanium nitride layer is formed. Is modified by a treatment using plasma. Then, an adhesion layer is completed by forming a second titanium nitride layer on the first titanium nitride layer whose surface layer has been modified. According to this manufacturing method, since the time required for executing the reforming step is short, it is possible to form a titanium nitride layer in which grains are discontinuously grown in a short time. Therefore, according to the present manufacturing method, it is possible to manufacture a semiconductor element having an adhesion layer that does not cause an increase in contact resistance or breakage of a diffusion layer even when high-temperature heat treatment is performed, in a short time and at low cost. Become.

Further, if the first titanium nitride layer forming step, the modifying step, and the second titanium nitride layer forming step are successively performed in the same chamber, the above characteristics can be obtained. A semiconductor element having an adhesion layer can be manufactured in a shorter time and at lower cost.

In the second method for manufacturing a semiconductor device,
As the reforming step, a step of reforming a surface layer of the first titanium nitride layer with argon plasma, a step of reforming a surface layer of the first titanium nitride layer with plasma of a gas containing nitrogen, and a step of reforming a gas containing oxygen A step of modifying the surface of the first titanium nitride layer with plasma can be employed. In the case where a reforming step using a plasma of a gas containing oxygen is employed, a layer containing oxygen exists between the first titanium nitride layer and the second titanium nitride layer. Therefore, the diffusion of the wiring metal is suppressed by the oxygen, so that it is possible to manufacture a semiconductor element having an adhesion layer in which the contact resistance is not increased due to the high-temperature heat treatment and the diffusion layer is hardly damaged.

The wiring metal layer forming step may be a step of forming a metal layer made of any material by any method. However, from a practical viewpoint, a metal layer made of tungsten is used. Is preferably formed by a chemical vapor deposition method.

[0018]

Embodiments of the present invention will be specifically described below with reference to the drawings. <First Embodiment> In the first embodiment, as shown in FIG. 1 (a), first, a Ti layer is formed on a substrate 101 having a contact hole for conducting with a diffusion layer by CVD.
The layer 102 is formed. By forming the Ti layer 102,
At the bottom of the contact hole (boundary between the Ti layer and the diffusion layer), Ti, which is a component of the Ti layer 102, and Si, which is a component of the diffusion layer, react with each other, as shown in FIG.
An iSi ₂ layer 103 is formed.

Next, as shown in FIG.
On the layer 102 and the TiSi ₂ layer 103, three layers of TiN
Form a layer. Specifically, first, TiCl ₄ , NH ₃ ,
The TiN layer 104 having a thickness of 5 to 30 nm is formed by a CVD method using N ₂ gas under the first film forming conditions described below.

First film forming conditions Film forming temperature: 630 ° C., film forming pressure: 20 torr TiCl ₄ flow rate: 40 sccm, NH ₃ flow rate: 60 sccm, N ₂
Flow rate: 3000 sccm Next, a TiN layer 105 having a thickness of ₂ to 5 nm is formed by the CVD method using TiCl ₄ , NH ₃ , and N ₂ gas. However, at this time, a second film forming condition different from the condition used when forming the TiN layer 104 is used.

Second film forming condition Film forming temperature: 630 ° C., film forming pressure: 20 torr TiCl ₄ flow rate: 4 sccm, NH ₃ flow rate: 60 sccm, N ₂ flow rate: 3000 sccm That is, the TiN layer 105 excludes the TiCl ₄ gas flow rate. The conditions are the same as those of the first film forming condition, and TiCl ₄
The film is formed under the second film forming condition in which the gas flow rate is smaller than the flow rate under the first film forming condition.

Then, under the same conditions as when forming the TiN layer 104 (that is, under the first film forming conditions), a C film having a thickness of 5 to 30 nm is formed.
The VD-TiN layer 106 is formed. In such a procedure,
After forming the TiN layers 104 to 106, a W layer 107 is formed by a CVD method as shown in FIG. Then, W wiring is formed by photolithography and etching.

When a semiconductor element (wiring) is formed according to the above procedure, the TiN layer 105 becomes
6 has finer grains. As a result, the grains of the TiN layer 106 are
It becomes discontinuous with a grain of 4. That is, the TiN layer 10
The portion composed of 4 to 106 has a structure in which W or Si does not easily diffuse inside. Therefore, even if a semiconductor element having an adhesion layer formed by this procedure is subjected to a high-temperature heat treatment for forming a capacitor or the like thereafter, the contact resistance may increase or the diffusion layer may be destroyed. Will not be.

In the first embodiment, the TiN layer 105
The flow rate of the TiCl ₄ gas at the time of film formation is set to
6 By making the flow rate different from the flow rate during film formation, Ti
T having finer grains than the N layers 104 and 106
Although the iN layer 105 is formed, for example,
Such a TiN layer 105 may be formed by changing other conditions such as the film forming pressure and the flow rates of NH ₃ and N ₂ gas. Also, it goes without saying that the film forming conditions for the TiN layers 104 and 106 may be different from the first film forming conditions described above. However, according to the first embodiment, since the condition changed when forming the TiN layers 104 to 106 is only the TiCl ₄ gas flow rate, the semiconductor element can be formed without complicating the manufacturing process. become.

In the first embodiment, three TiN layers are formed. However, a film forming step under the second film forming condition and a film forming step under the first film forming condition are added to form a TiN layer.
The number of iN layers may be increased. In addition, W is used as a wiring metal.
Naturally, other materials may be used.

<Second Embodiment> In the second embodiment, argon plasma is used to form an adhesion layer having discontinuous grains.

Specifically, first, as shown in FIG.
As described above, contact holes for establishing conduction with the diffusion layer
On the opened substrate 201, a Ti layer 202 (and a Ti layer
Si _TwoA layer 203) and a TiN layer 204. What
The procedure for forming the Ti layer 202 and the TiN layer 204 (film formation method)
Method, conditions, and film thickness) of the Ti layer 10 in the first embodiment.
2. The same procedure as used for forming the TiN layer 104 is used.
You. Therefore, TiS is provided at the bottom of the contact hole._TwoLayer 2
03 is formed.

Next, as schematically shown in FIG. 2B, the surface of the TiN layer 204 is irradiated with argon ions (Ar ⁺ ) by applying argon plasma in a chamber in which the TiN layer 204 is formed. The TiN layer 204
Thin (several nm thick) amorphous TiN layer 20 on the surface layer of
5 is formed. In this embodiment, during this process, the film forming temperature is 630 ° C., the film forming pressure is 1 torr, and the Ar flow rate is 30.
The condition of this treatment is that the TiN layer 204
Any material can be used as long as it can be made amorphous.

Then, after forming the TiN layer 206 having a thickness of 5 to 30 nm under the same conditions as when forming the TiN layer 204 (ie, under the first film forming conditions described in the first embodiment),
By forming the W layer 207 by the CVD method, the structure shown in FIG. 2C is obtained. Then, W wiring is formed by photolithography and etching.

When a semiconductor element (wiring) is formed according to the above procedure, the TiN layer 206 becomes amorphous T
Since it grows on the iN layer 205, the TiN layer 2
The grains of 06 become discontinuous with the grains of the TiN layer 204. That is, the TiN layer 204, the amorphous Ti
The portion composed of the N layer 205 and the TiN layer 206 has a structure in which W or Si hardly diffuses inside.
For this reason, the semiconductor element having the adhesion layer formed by this procedure may cause an increase in the contact resistance and the destruction of the diffusion layer even if a high-temperature heat treatment is subsequently performed for forming a capacitor or the like. There will be no. And
By using this procedure, such an adhesion layer can be formed by continuous processing in the same chamber, so that even if a high-temperature heat treatment is performed, the adhesion layer does not increase in contact resistance or cause damage to the diffusion layer. Can be manufactured in a short time and at low cost.

<Third Embodiment> In the third embodiment, NH ₃ plasma is used to form an adhesion layer having discontinuous grains.

Specifically, first, as shown in FIG.
As described above, contact holes for establishing conduction with the diffusion layer
On the opened substrate 301, a Ti layer 302 (and a Ti layer
Si _TwoA layer 303) and a TiN layer 304 are formed. What
The procedure for forming the Ti layer 302 and the TiN layer 304 (film formation method)
Method, conditions, and film thickness) of the Ti layer 10 in the first embodiment.
2. The same procedure as used for forming the TiN layer 104 is used.
You.

Next, as shown schematically in FIG. 3B, the surface of the TiN layer 304 is exposed to NH ₃ plasma in a chamber in which the TiN layer 304 is formed, so that the TiN layer 304 contains more N. TiN layer 30 as a layer
Reform to 5. In this embodiment, in this process, the film forming temperature is 630 ° C., the film forming pressure is 5 torr, and the NH ₃ flow rate is 5
The condition of this treatment is that the TiN layer 304
Any material that can change the fine structure of the surface layer may be used.

Then, after forming the TiN layer 306 having a thickness of 5 to 30 nm under the same conditions as when forming the TiN layer 304 (ie, under the first film forming conditions described in the first embodiment),
A W layer 307 is formed by a CVD method to obtain a structure shown in FIG. Then, W wiring is formed by photolithography and etching.

When a semiconductor element (wiring) is formed in the above-described procedure, the TiN layer 306 grows on the nitrided TiN layer 305 having a surface state different from that of the TiN layer 304. Grain is TiN
The grains of the layer 304 become discontinuous. That is, TiN
The portion consisting of the layer 304, the nitrided TiN layer 305, and the TiN layer 306 has a structure in which W or Si hardly diffuses inside. For this reason, the semiconductor element having the adhesion layer formed by this procedure may cause an increase in the contact resistance and the destruction of the diffusion layer even if a high-temperature heat treatment is subsequently performed for forming a capacitor or the like. There will be no. By using this procedure, such an adhesion layer can be formed by continuous processing in the same chamber, so that even if a high-temperature heat treatment is performed, an increase in contact resistance and a destruction of the diffusion layer do not occur. A semiconductor element having an adhesion layer can be manufactured in a short time and at low cost.

<Fourth Embodiment> In the fourth embodiment, O ₂ plasma is used to form an adhesion layer having discontinuous grains.

Specifically, first, as shown in FIG.
As described above, contact holes for establishing conduction with the diffusion layer
On the opened substrate 401, a Ti layer 402 (and Ti
Si _TwoLayer 403) and the TiN layer 404,
In the first embodiment, the Ti layer 102 and the TiN layer 104
It forms by the same procedure used for formation.

Next, as schematically shown in FIG. 4B, the surface layer of the TiN layer 404 is oxidized by blowing O ₂ plasma in a chamber in which the TiN layer 404 is formed, and titanium, oxygen and Thin (several nm thick) made of nitrogen
A Ti-ON layer 405 is formed. In this embodiment, the film forming temperature is 630 ° C. and the film forming pressure is 5 to
Although the flow rates of rr and O ₂ were set to 500 sccm, the condition of this treatment may be any condition as long as the surface layer of the TiN layer 404 can be changed to a Ti—O—N layer by oxidation.

Then, under the same conditions as when forming the TiN layer 404 (that is, under the first film forming conditions described in the first embodiment), a TiN layer 406 having a thickness of 5 to 30 nm is formed. Is plasma-oxidized under the same conditions as when the Ti-ON layer 405 is formed, thereby forming the Ti-ON layer 4.
07 is formed. After that, a W layer 408 is formed by the CVD method to obtain the structure shown in FIG. Then, W wiring is formed by photolithography and etching.

When a semiconductor element (wiring) is formed in the above-described procedure, the TiN layer 406 grows on the Ti-ON layer 405 having a surface state different from that of the TiN layer 404. The grains of the TiN layer 406 are Ti
It becomes discontinuous with the grains of the N layer 404. That is, Ti
N layer 404, Ti-ON layer 405, TiN layer 406,
The portion composed of the Ti-ON layer 407 is made of W or Si
Has a structure that is difficult to diffuse inside. For this reason, the semiconductor element having the adhesion layer formed by this procedure may cause an increase in the contact resistance and the destruction of the diffusion layer even if a high-temperature heat treatment is subsequently performed for forming a capacitor or the like. There will be no.

The semiconductor element formed by this procedure has a layer containing oxygen, such as the Ti-ON layer 405 and the Ti-ON layer 407, between W and the substrate (Si). . Therefore, the diffusion of W (or Si) is also suppressed by the oxygen, and therefore, if this manufacturing procedure is used, compared with the manufacturing procedure described in the first to third embodiments, the use of this manufacturing procedure causes the high-temperature heat treatment. In addition, it is possible to manufacture a semiconductor element in which the contact resistance is not increased and the diffusion layer is less likely to be broken. And if this procedure is used, such an adhesion layer can be formed by continuous processing in the same chamber.
Even if high-temperature heat treatment is performed, a semiconductor element having an adhesion layer that does not cause an increase in contact resistance or breakage of a diffusion layer can be manufactured in a short time and at low cost.

[0042]

As described above, according to the present invention,
Even if high-temperature heat treatment is performed, a semiconductor element having an adhesion layer that does not cause an increase in contact resistance or breakage of a diffusion layer can be manufactured in a short time and at low cost.

[Brief description of the drawings]

FIG. 1 is a process chart for explaining a first embodiment of the present invention.

FIG. 2 is a process chart for explaining a second embodiment of the present invention.

FIG. 3 is a process chart for explaining a third embodiment of the present invention.

FIG. 4 is a process chart for explaining a fourth embodiment of the present invention.

[Explanation of symbols]

101, 201, 301, 401 Substrate 102, 202, 302, 402 Ti layer 103, 203, 303, 403 TiS ₂ layer 104-106, 204, 206, 304, 306, 4
04,406 TiN layer 205 Amorphous TiN layer 305 TiN nitride layer 405,407 Ti-ON layer 107,207,307,408 W layer

Claims (9)

[Claims] 1. A titanium layer forming step of forming a titanium layer in which a portion in contact with a diffusion layer is silicided on a semiconductor element substrate having a contact hole formed therein, and a titanium layer formed by the titanium layer forming step. ,
A first titanium nitride layer forming step of forming a first titanium nitride layer by a chemical vapor deposition method using a first film forming condition, and a first titanium nitride layer formed by the first titanium nitride layer forming step Forming a second titanium nitride layer having a smaller grain size than the first titanium nitride layer by a chemical vapor deposition method using a first deposition condition different from the first deposition condition; Forming a third titanium nitride layer on the second titanium nitride layer formed by the titanium nitride layer forming step and the second titanium nitride layer forming step by a chemical vapor deposition method using the first film forming condition; Forming a third titanium nitride layer, and forming a wiring metal layer on the third titanium nitride layer formed by the third titanium nitride layer forming step. A method for manufacturing a semiconductor device. 2. The first to third titanium nitride film forming steps are both steps of forming a titanium nitride film by a chemical vapor deposition method using TiCl ₄ , NH ₃ , and N ₂ gas. the second film forming conditions, the conditions except for the TiCl ₄ gas flow rate is the same as the conditions of the first deposition condition, TiCl ₄
2. The method according to claim 1, wherein a gas flow rate is smaller than a flow rate of the first film forming condition. 3. A titanium layer forming step of forming a titanium layer in which a portion in contact with a diffusion layer is silicided on a semiconductor element substrate having a contact hole, and a step of forming a titanium layer on the titanium layer formed by the titanium layer forming step. ,
A first titanium nitride layer forming step of forming a first titanium nitride layer by a chemical vapor deposition method using a first film forming condition, and a first titanium nitride layer formed by the first titanium nitride layer forming step A plasma treatment to modify the surface layer of the first titanium nitride film; and forming the first film forming condition on the first titanium nitride layer whose surface layer is modified by the reforming step. A second titanium nitride layer forming step of forming a second titanium nitride layer by a chemical vapor deposition method using GaN, and a wiring layer on the second titanium nitride layer formed by the second titanium nitride layer forming step. Forming a wiring metal layer for forming the above metal layer. 4. The method according to claim 3, wherein the step of forming the first titanium nitride layer, the step of modifying and the step of forming the second titanium nitride layer are continuously performed in the same chamber.
A method for manufacturing a semiconductor device according to claim 4. 5. The method according to claim 3, wherein the modifying step is a step of modifying a surface layer of the first titanium nitride layer with argon plasma. 6. The semiconductor device according to claim 3, wherein the reforming step is a step of reforming a surface layer of the first titanium nitride layer with a plasma of a gas containing nitrogen. Production method. 7. The semiconductor device according to claim 3, wherein the reforming step is a step of reforming a surface layer of the first titanium nitride layer with a plasma of a gas containing oxygen. Production method. 8. A method according to claim 1, further comprising, between the step of forming the second titanium nitride layer and the step of forming the wiring metal layer, a second oxidation step of modifying a surface layer of the second titanium nitride layer with a plasma of a gas containing oxygen. The method for manufacturing a semiconductor device according to claim 7, wherein: 9. The semiconductor device according to claim 1, wherein said wiring metal layer forming step is a step of forming a metal layer made of tungsten by a chemical vapor deposition method. Manufacturing method.