JPH0344922A - Manufacture of semiconductor device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor device, and particularly to an improvement in a method for forming an ohmic contact layer in a semiconductor device.

[Prior Art] Conventionally, in a method for manufacturing a semiconductor device, Aβ or Aβ is diffused into a diffusion layer as an active layer formed on a Si substrate.
For cotton contact, in order to reduce the resistance at the contact part, normally a Ti layer is formed on the diffusion layer at the contact opening, and then this Ti layer is heat-treated in an N2 atmosphere. By doing so, a low resistance TiN/TiSi* layer is formed as an ohmic contact layer.

[Problems to be Solved by the Invention] In the method for forming an ohmic contact layer in the conventional semiconductor device described above, the low resistance TiN/TiS
When forming the i* layer, generally, Ti diffuses into the Si substrate and, by extension, into the diffusion layer faster in the surface direction than in the depth direction of the diffusion layer. Since diffusion may cause, for example, peeling of the insulating film thereon, the Ti layer cannot be subjected to high temperature heat treatment, and the heat treatment temperature is limited to approximately 600°C. However, when the Ti layer is subjected to N heat treatment at about 600°C in an atmosphere, the low resistance Ti layer is effectively used as an ohmic contact layer.
There were problems in that it was difficult to form the 5iz layer, and it was also impossible to form a TiN layer as a barrier layer on the surface of the Ti layer.

This invention was made to solve these conventional problems, and its purpose is to enable high-temperature heat treatment of the Ti layer and to form an effective low-resistance TiN layer as an ohmic contact layer. Two TiSi layers were formed. An object of the present invention is to provide a method for manufacturing this type of semiconductor device, in this case a method for forming an ohmic contact layer.

[Means for Solving the Problems] In order to achieve the above object, a method for manufacturing a semiconductor device according to the present invention includes the steps of: diffusing a Ti layer formed on a diffusion layer exposed in a contact opening by high-temperature heat treatment; Low-resistance Ti5iJJ is formed in almost the same area as the opening without being diffused in the surface direction of the layer, and TiN is also deposited on the surface.
It is designed to form layers.

That is, the present invention includes a step of opening a contact opening for an electrode contact to the diffusion layer in an insulating film formed on a Si substrate having a diffusion layer, and forming a Ti layer on the insulating film including the contact opening. After forming a film and implanting Si ions into the Ti layer, a high temperature heat treatment is performed in a nitrogen atmosphere, or a surface portion of the diffusion layer exposed in the contact opening is partially dug, After filling this dug portion with a Ti layer, high-temperature heat treatment is performed in an N2 atmosphere to form a low-resistance T layer as an ohmic contact layer.
a step of forming an iN/Ti5La layer; and a step of forming an iN/Ti5La layer;
This method of manufacturing a semiconductor device includes at least a step of forming an electrode and a wiring layer on the TiSix layer.

[Effect]

Therefore, in the method for manufacturing a semiconductor device according to the present invention, after forming a Ti layer on an insulating film including a contact opening and implanting Si ions, a high temperature heat treatment is performed in an N2 atmosphere, or After partially digging the surface of the diffusion layer exposed in the opening and filling the dug part with a Ti layer, a low-resistance TiSi□ is formed as an ohmic contact layer by performing high-temperature heat treatment in an N2 atmosphere. At the same time, a TiN layer serving as a barrier layer can be formed on the surface of the TiN layer.

(Example 1) Hereinafter, various examples of the method for manufacturing a semiconductor device according to the present invention will be described in detail with reference to FIGS. 1 and 2.

FIGS. 1A to 1E are cross-sectional views sequentially schematically showing the steps of manufacturing a semiconductor device to which the method of the first embodiment of the present invention is applied.

That is, in FIG. 1, the method of the first embodiment first forms an insulating film 3 with a thickness of about 1 μm on the entire surface of a Si substrate 1 on which a diffusion layer 2 is selectively formed. The insulating film 3 is selectively etched away by conventionally known photolithography and etching methods to selectively open contact openings 8 for electrode contact with the diffusion layer 2 (see FIG. 1). (a)).

Further, after forming a Ti layer 4 with a thickness of about 200 to 400 layers on the insulating film 3 including the contact opening 8 using a sputtering method or the like (FIG. 2(b)), the contact opening 8 is Si ions 5 are injected into the Ti layer 4 formed on the portion 8 by ion implantation at a voltage of about 10 keV.
Inject about 10"1oz/cm" ((C) in the same figure)
.

Next, the Si-injected Ti layer 4 is heat-treated at a high temperature of about 700 to 900° C. in an N2 atmosphere to form a TiN/TiSi2 layer 6 as an ohmic contact layer. Same figure (d)
), then a sputtering method or the like is applied to the TiN/TiSi2 layer 6 to form an A [or AI2 alloy layer 7 that will become the electrode and wiring layer.
(e) of the same figure), the A°C or A2 alloy layer γ and the TiN/TiSi layer 6 are selectively patterned and formed by photolithography and etching to form the desired shape. Electrodes and wiring layers are obtained.

Therefore, in the method of this first embodiment, Si is added to the Ti layer.
Because ions are implanted, diffusion from the Ti layer toward the surface of the diffusion layer during high-temperature heat treatment is effectively suppressed, and in this state, a low-resistance Ti5ia layer is formed as an ohmic contact layer, and At the same time, a TiN layer as a barrier layer made of Ti nitride is also formed on the surface.

Next, FIGS. 2(a) to 2(gl) are sectional views each schematically showing the steps of manufacturing a semiconductor device to which the second embodiment method of the present invention is applied.

That is, also in FIG. 2, the method of the second embodiment is as follows:
First, as in the case of the method of the first embodiment, a substrate 31 is provided with a diffusion layer 2 selectively formed thereon, and an I
An insulating film 3 is formed to a thickness of approximately 1.0 am, and a resist pattern 9 for electrode contact with the diffusion layer 2 is formed by photolithography (FIG. 2(a)).
Using this resist pattern 9 as a mask, the insulation 11i3 is selectively etched away by an etching method to selectively open a contact opening 8 for an electrode contact.
The etching gas is filled with CF, and a dry etching method or a wet etching method is used at a low vacuum so that the etching opening area of the contact opening 8 is somewhat larger than the opening area of the pattern (FIG. 3(b)). ).

Further, the surface portion of the diffusion layer 2 exposed in the contact opening 8 is partially dug to a depth of approximately 400 mm by dry etching to form a dug portion 2a (see FIG. C)), a resist pattern 9 including these dug portions 2a and contact openings 8 in the insulating film 3;
A Ti layer 4 having a thickness of about 400 to 500 layers is formed on the top using a sputtering method or the like. At this time, since the resist pattern 9 is overhanging in the contact opening 8, the formation is difficult. The Ti layer 4 is not deposited on the inner side surface of the contact opening 8 including the opening of the insulating film 3, but is deposited on the bottom surface of the contact opening 8, that is, the surface dug portion of the diffusion layer 2. 2a (same figure (dll.

Subsequently, the resist pattern 9 is removed by a lift-off method, but at this time, the T on this resist pattern 9 is removed.
The i layer 4 is also removed at the same time, and in the contact opening 8, the diffusion layer 2 buried with the Ti layer 4 is removed.
The surface digging portion 2a is exposed (as shown in the same figure).
e)). Further, the Ti layer 4 in which the dug portion 2a of the diffusion layer 2 was buried was heated to about 750 to 850 nm in N2 atmosphere.
Here, by heat treatment at a high temperature of about 0°C, the TiN layer 6a and the TiSi layer as an ohmic contact layer are bonded.
The x layer 6b is formed without being diffused toward the surface of the Si substrate 1 (FIG. 1(f)), and then these TiN,
Electrodes are formed on the TiSix layers 6a and 6b by sputtering or the like.
To form the A°C or 1-alloy layer 7 that will become the wiring layer, the same figure (
g)) Thereafter, these l or he2 alloy layers 7 are selectively patterned and formed by photolithography and etching as in the conventional method to obtain the desired electrodes and wiring layers. .

Therefore, in this square 2 embodiment method as well, the same effects as in the first embodiment method can be obtained, and here,
Since a part of the surface of the diffusion layer is dug, this occurs when impurities are implanted into the diffusion layer and remains even after activation. Since the so-called damaged layer is removed, a more effective ohmic contact structure can be obtained.

[Effect of the invention 1 As detailed above, according to the method of this invention, a contact opening for an electrode contact to the diffusion layer is formed in an insulating film formed on a Si substrate having a diffusion layer. in,
After forming a Ti layer on the insulating film including the contact opening and implanting Si ions, a high-temperature heat treatment is performed in an N2 atmosphere, or a portion of the surface of the diffusion layer exposed in the contact opening is After digging the trench and filling the dug portion with a Ti layer, high-temperature heat treatment is performed in an N2 atmosphere, which effectively prevents the diffusion of the diffusion layer from the Ti layer toward the surface during the high-temperature heat treatment. A low-resistance Ti5iz layer as an ohmic contact layer and a TiN layer as a barrier layer made of Ti nitride on the surface can be formed at the same time. In addition to obtaining a highly reliable ohmic contact structure, when digging into a portion of the surface of the diffusion layer, the damaged layer left on the surface is removed, resulting in a better ohmic contact. It has excellent features such as the manufacturing process itself being relatively simple and easy to implement.

[Brief explanation of drawings]

FIG. 1 (al to e) and FIG. 2 (al to gl) each schematically show sequentially the manufacturing process of a semiconductor device to which the method of the first and second embodiments of the present invention is applied. It is a sectional view. 1... Si substrate, 2... Diffusion layer, 2a...
...Dug portion, 3...Insulating film, 4...Tx
N, 5...Si ion, 6...TiN/
TiSi2 layer, 6a---TiN layer, 6b...''T
i5xi layer, ...A°C or 12 alloy layer, ...contact opening, ...resist pattern.

Claims (1)

[Claims] A step of opening a contact opening for an electrode contact to the diffusion layer in an insulating film formed on a Si substrate having a diffusion layer, and forming a Ti on the insulating film including the contact opening.
After forming the Ti layer and implanting Si ions into the Ti layer, a high-temperature heat treatment is performed in an N_2 atmosphere, or a surface portion of the diffusion layer exposed in the contact opening is partially dug. After filling this dug portion with a Ti layer, high-temperature heat treatment is performed in an N_2 atmosphere to form a low-resistance TiN/TiSi_2 layer as an ohmic contact layer.
A method for manufacturing a semiconductor device, comprising at least the steps of forming a layer, and forming an electrode and a wiring layer on the TiN/TiSi_2 layer.