JPS5823738B2 - Manufacturing method of semiconductor device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a semiconductor device.

A region of one conductivity type of the semiconductor substrate is connected to an external wiring by providing an opening in a portion of an insulating layer deposited on the surface of the substrate located above the region, and covering the conductivity type region with electrode metal through the opening. I'll put it on and go.

However, it is difficult to align the conductivity type region and the connection hole, and it is necessary to first form a large conductivity type region.

This has caused a reduction in the degree of integration of semiconductor devices, especially integrated circuits.

In addition, when forming electrodes for integrated circuits, etc., it is preferable that the metal used as the electrode material forms a direct contact with the semiconductor substrate, and for this purpose, aluminum is often used because it easily forms ohmic contact with the semiconductor. When used, it is not possible to compensate for the above-mentioned alignment error between the conductivity type region and the connection hole.

The present invention has been made in view of these problems, and at the same time obtains good contact for electrode formation.
The present invention is intended to compensate for alignment errors, and embodiments of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a semiconductor substrate of one conductivity type, for example, an N-type silicon substrate, on which P-type head regions 2, 2.2 are formed by diffusing P-type impurities at appropriate locations. There is.

3 is a surface protection film made of a silicon oxide film or the like provided to protect the substrate surface; 4°4.4 is the P-type head region 2, 2
．． Normally, the opening 4° 4.4 exposes the surface portion of each P-type head region 2, 2.2, Depending on the error in the alignment of the holes 4, 4.4, the holes 4, 4.4 often do not cover the N-type substrate surface 5 other than the P-type head area 2, 2.2. may also be exposed.

As the next step, as shown in FIG.
, 4+ While adding impurity boron (B), molybdenum (
Mo) is deposited to form a boron-doped molybdenum thin film 6.

At this time, while molybdenum was deposited on the substrate 1 by a hydrogen reduction method of molybdenum chloride (MoC15), boron was added by sending boron bromide (BBr3) gas.

The molybdenum thin film 6 has been used for 5,000 years.

Next, the substrate 1 was left in a hydrogen atmosphere at a temperature of 0.0°C for 20 minutes to diffuse boron (B) in the molybdenum thin film 6 to the exposed surface 5 of the substrate, as shown in FIG. In this way, a P-type diffusion supplement layer 7 is formed on the substrate surface 5 in direct contact with the molybdenum thin film 6.

Since this diffusion supplement layer 7 has the same conductivity type as the P-type region 2,
electrically connected, and as a result this replenishment layer 7
This serves to prevent the molybdenum thin film 6 from coming into direct contact with the substrate surface 5.

Further, the contact between the molybdenum thin film 6 and the P-type regions 2, 2.degree. 2 is a very stable ohmic contact since the molybdenum thin film 6 is doped with P-type impurities.

As is clear from the above description, the present invention provides an opening in an insulating film to expose a region of one conductivity type on the surface of a substrate, and adds an impurity of the same conductivity type as the region of one conductivity through the opening. Metallic molybdenum is deposited on the surface of the substrate, and impurities added to the metal molybdenum are diffused into the exposed substrate surface through the above-mentioned openings through a subsequent heat treatment to form one conductivity type that is connected to the above-mentioned -conductivity type region. Since the diffusion fill layer is formed, direct contact between the substrate and the metal molybdenum is prevented, and even if the center of the opening deviates from the center of the one-conductivity type region, it will not be affected! It is possible to replenish the region of one conductivity type under the hole, and molybdenum does not come into undesired contact with regions other than the above-mentioned -conductivity type region.

Therefore, unlike the conventional method, it is not necessary to plan for the center deviation between the two and make the area of one conductivity type region larger than the opening for obtaining an ohmic contact, and it is no longer necessary to make the area of the one conductivity type region larger than the opening for obtaining an ohmic contact. The area of the region can be reduced and the storage capacity within the substrate can be increased, thereby promoting higher integration of semiconductor devices, especially integrated circuits.

It is said that ohmic contact between metal molybdenum and a semiconductor cannot be achieved by mere heat treatment, but as in the present invention, it is possible to make ohmic contact between molybdenum and a semiconductor by adding impurities of the same conductivity type to the molybdenum as in the present invention. By employing a heat treatment method, good ohmic contact can be obtained between the semiconductor and molybdenum, and ohmic contact in integrated circuits can be easily formed.

[Brief explanation of drawings]

1 to 3 are cross-sectional views showing the method of the present invention in the order of steps, in which 2 is a P-type region, 4 is an opening, 5 is an exposed substrate surface, 6 is a molybdenum thin film, 7 is a diffusion fill layer, are shown respectively.

Claims (1)

[Claims] 1 An opening is provided in an insulating film deposited on the surface of a semiconductor substrate to expose a region of one conductivity type selectively provided on the surface of the substrate, and an impurity of one conductivity type is formed on the surface of the substrate exposed through the opening. The impurities added to the metal molybdenum are grown from the exposed surface of the substrate by growing the metal molybdenum while adding the metal molybdenum, and then heat-treated to diffuse the impurities added to the metal molybdenum from the exposed substrate surface. In addition, a diffusion fill layer of one conductivity type connected to the one conductivity type region is formed on the surface of the substrate other than the one conductivity type region to prevent direct contact between the substrate and metal molybdenum. A method for manufacturing a semiconductor device.