JPH05166754A - Manufacture or semiconductor device - Google Patents

Abstract

PURPOSE:To flatten a contact hole by laminating a selectively grown base layer to become a seed of a selective growth only at a sidewall of a contact hole and selectively growing a conductive film from the sidewall. CONSTITUTION:A Ti layer 6 to become a seed of a selective growth is laminated on the entire surface of an Si substrate 1 having contact holes 4, 5. Then, a part of the layer 6 except the layer 6 laminated on the sidewalls 4a, 5a of the holes 4, 5 is formed on a nonselected base layer 7. In this case, nitrogen ions are implanted at '0' degree of an implantation angle. As a result, a TiN film is formed as the layer 7. Then, tungsten is selectively grown to form tungsten films only on the Ti layers of the sidewalls 4a, 5a of the holes 4, 5, and the hole 5 is buried with a tungsten film 8 in a thickness of substantially half of the contact size. Thus, even if the thickness of the grown film is different according to the base film, the holes of different depths can be flattened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a contact embedding technique for simultaneously embedding tungsten in contact holes having different depths in LSIs such as MOS transistors and bipolar transistors.

[0002]

2. Description of the Related Art In the conventional filling method of this type, as shown in FIG. 6, contact holes 43 having different depths are formed between interlayer insulating films composed of upper and lower insulating films 41, 42. A method of embedding 44 with a tungsten film 45 is adopted. However, (i) since tungsten selectively grows from the bottoms of the contact holes 43 and 44, even if the tungsten film 45 is embedded in the shallow contact hole 44, the deep contact hole 43 is not yet embedded with tungsten, It is difficult to flatten the contact holes 43 and 44. (Ii) Moreover, the growth thickness of the tungsten film 45 varies depending on the underlying film 46 of the Si film, the WSi film, or the polysilicon film, and the growth of the film thickness is uneven. (Iii) As shown in FIG. 7, the base of the contact hole 54 provided in the insulating film 53 is, for example, Si having the n ⁺ layer 52.
When the substrate 51 is used, the reaction with Si cannot be suppressed during the selective growth of the tungsten film 55, which may cause a junction leak. (Iv) In addition, the deposition rate of tungsten becomes slow, and the number of wafers processed per unit time may deteriorate so-called throughput.

[0003]

According to the present invention, a conductive material is selectively grown in a contact hole for electrically connecting an upper wiring and a lower wiring of a transistor and / or an impurity diffusion layer of a semiconductor substrate. At this time, a selective growth underlayer, which is capable of growing a conductive material and is a seed for selective growth of a conductive film, is stacked on the entire surface of the semiconductor substrate including the contact holes, and then ion implantation and heat treatment are sequentially applied to the contact. Since the part of the selective growth underlayer other than the side wall of the hole is formed as a non-selective growth underlayer capable of suppressing the growth of the conductive material, the conductive material is selectively grown to fill the contact hole with the conductive film. Another method of manufacturing a semiconductor device. That is, according to the present invention, a selective growth underlayer serving as a seed for selective growth is stacked only on the side wall of the contact hole, and the conductive film is selectively grown from the side wall. In the present invention, for example, when three contact holes 31, 32, 33 having different depths are simultaneously filled with tungsten in FIG.
Selective growth underlayers 34, 35, 3 on the sidewalls of 1, 32, 33
6 parts are formed. On the other hand, each contact hole 3
The non-selective growth underlayers 34a, 34b, 35a, 3 are formed on the bottom portions of 1, 32, 33 and the flat portion 38 between the contact holes.
5b, 36a, 36b are formed. This non-selective growth base layer is formed by performing ion implantation, for example. That is, ion implantation is performed so that the selective growth underlayer formed on the entire surface of the semiconductor substrate is not implanted into the sidewall of the contact hole. As a result, a part of the selective growth underlayer changes into a non-selective growth underlayer that does not become a seed for selective growth of the conductive film. Then, the conductive material is selectively grown. At this time, during the selective growth, as shown in FIG. 3, the conductive film 39a is selectively grown from the sidewalls of the contact holes 31, 32, and 33. Then, as shown in FIG. 4, the contact holes 31, 32, and 33 are filled with a conductive film 39 to complete the selective growth. On the other hand, as shown in FIG.
Since the growth selectively occurs from the bottoms of the contact holes 6 and 63, the contact holes 62 are shallower than the contact holes 6 although the conductive film 65 is sufficiently filled.
In Example 3, the conductive film 66 protruded, and the conductive film 64 was insufficiently embedded in the deepest contact hole 61, so that it was difficult to flatten the contact hole. The present invention solves these problems.

[0004]

Embodiments of the present invention will be described below. The present invention is not limited to this. Gate 1 of MOS transistor and its Si substrate 2
In selectively growing tungsten (conductive material) in the shallow contact hole 4 and the deep contact hole 5 for electrically connecting to the impurity diffusion layer 3 of the above, first, as shown in FIG. 1, the contact holes 4 and 5 are included. On the entire surface of the Si substrate 2, a Ti layer (selective growth underlayer) 6 serving as a seed for selective growth is laminated. At this time, the thickness of the Ti layer is 500
It is preferable to form it in the range of 1000 Å. The depth of the shallow contact hole 4 is 0.3 μm, and the opening diameter is 0.
3 μm, that of deep contact hole 5 is 1.0
˜2.0 μm is preferable, but in this embodiment, it is 1.5 μm, and the opening diameter is 0.3 μm. Subsequently, ion implantation and heat treatment are sequentially applied to form a portion of the Ti layer 6 excluding the Ti layer 6 laminated on the sidewalls 4a and 5a of the contact holes 4 and 5 in the non-selective growth underlayer 7 (FIG. 1). reference). At this time, the ion implantation is performed at an implantation angle of 0 degree so that the nitrogen ions are 10 times.
Implant energy of ~ 50 keV and 10 ¹⁵ ~ 10 ¹⁶ c
The ion implantation amount is m ⁻² . As a result, a TiN film is formed as the non-selective growth underlayer 7. This TiN film is T
The i-layer 6 may be formed only on the surface layer (several tens of liters).
Further, oxygen ions may be used instead of nitrogen ions. In this embodiment shown in FIG. 1, T in the region other than the sidewalls 4a and 5a is
It is shown that the TiN film 7 as a non-selective growth underlayer is formed on the surface of the i layer 6. Also, the heat treatment is R
300 to 700 ° C. under N ₂ atmosphere using TA treatment
The heat treatment temperature is applied in a short time of several minutes. Furnace annealing may also be used. Then, selective growth of tungsten is performed to form the contact hole 4.5 in a tungsten film (conductive film).
8 (see FIG. 2). At this time, WF ₆ and H ₂ are reacted at about 250 ° C. to 300 ° C.
The tungsten film is formed only on the Ti layer 6 on the side walls 4a and 5a of the metal film 5. As described above, in this embodiment, the underlying gate 1
Also, regardless of the presence of the impurity diffusion layer 3 of the Si substrate 2, the contact hole 5 can be filled with the tungsten film (conductive film) 8 with a film thickness of about half the contact size.

[0005]

As described above, according to the present invention, the selective growth underlayer serving as a seed for selective growth is laminated only on the side wall of the contact hole, and the conductive film is selectively grown from the side wall. Thus, even if the grown film thickness is different, it is possible to flatten the contact hole at different depths. Moreover, even if the base of the contact hole is, for example, an impurity diffusion layer of the semiconductor substrate, there is no possibility of suppressing the reaction with Si during selective growth of the conductive film and causing a junction leak. In addition, there is no fear that throughput will deteriorate.

[Brief description of drawings]

FIG. 1 is a structural explanatory view showing a first step of a manufacturing method according to an embodiment of the present invention.

FIG. 2 is a structural explanatory view showing a second step of the manufacturing method in the above embodiment.

FIG. 3 is a manufacturing process explanatory view showing the principle of the manufacturing method of the present invention.

FIG. 4 is a manufacturing process explanatory view showing the principle of the manufacturing method of the invention following the process of FIG. 3;

FIG. 5 is a manufacturing process explanatory view showing the principle of a conventional manufacturing method.

FIG. 6 is a configuration explanatory view showing one step of a conventional manufacturing method.

FIG. 7 is a structural explanatory view showing one step of a conventional manufacturing method.

[Explanation of symbols]

 1 gate 2 Si substrate 3 impurity diffusion layer 4 shallow contact hole 5 deep contact hole 6 Ti layer (selective growth underlayer) 7 TiN layer (non-selective growth underlayer) 8 tungsten film (conductive film)

Claims (4)

[Claims] 1. When a conductive material is selectively grown in a contact hole for electrically connecting an upper layer wiring and a lower layer wiring of a transistor, and / or a gate and an impurity diffusion layer of a semiconductor substrate, a semiconductor substrate including a contact hole is formed. A selective growth underlayer that allows growth of a conductive material and serves as a seed for selective growth of a conductive film is laminated on the entire surface of the substrate, and then ion implantation and heat treatment are sequentially performed to remove the sidewalls of the contact holes. Is formed in a non-selective growth underlayer capable of suppressing the growth of the conductive material, and then the conductive material is selectively grown to fill the contact hole with the conductive film. 2. The method for manufacturing a semiconductor device according to claim 1, wherein the conductive film is a tungsten film and the selective growth underlayer is a Ti layer, a tungsten layer or a Si layer. 3. The non-selective growth underlayer is a TiO ₂ layer or TiN.
The method for manufacturing a semiconductor device according to claim 1, wherein the semiconductor device is a layer. 4. The RTA in which the heat treatment is a short-time anneal.
The method for manufacturing a semiconductor device according to claim 3, which is performed by a method.