JPS5844761A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a high resistance under a photomask and a conductive layer on the region except the mask by accumulating a polycrystalline Si layer through an insulating film on a semiconductor substrate when a high resistance is formed at the semiconductor device with polycrystalline Si, covering the high resistance region to be obtained with the photomask and ion implanting on the entire surface. CONSTITUTION:A thick field oxidized film 22 and a thin gate oxidized film 23 are covered on an Si substrate 21, and a contacting hole 24 for connecting directly the polycrystalline Si wirings to a diffused layer is opened at the film 23. A polycrystalline Si layer is accumulated on the entire surface, is etched, and a polycrystalline Si layer 26 which is contacted with the drain region formed later and a polycrystalline Si electrode 25 laid under the film 23 remain. Thereafter, a photoresist mask 20 is formed on the high resistance 29 to be obtained later, ions are implanted, thereby forming a source region 30 and a drain region 31. Simultaneously, conductivity is provided to the Si layer 26 which is contacted with the electrode 25 and the region 31, and the Si layer 26 under the mask 20 remains as the high resistance, thereby forming a resistor 29.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a semiconductor device, and particularly to a technique using polycrystalline silicon as a high resistance material.

In semiconductor integrated circuit devices, it is often necessary to realize very high resistance within a small area. For example, a load resistor in an MO8 type integrated circuit is one example. It has been known for a long time that polycrystalline 7-licon, which does not contain any impurities or contains only trace amounts of impurities, is one of the materials suitable for this purpose. In addition, a conventionally known method for actually incorporating it into a semiconductor device is to add a step of growing high-resistance polycrystalline silicon and a photoresist step of molding it into a predetermined shape to the base process. It is. FIG. 1 shows a conventional technique for adding high resistance using polycrystalline silicon, taking as an example a normal aluminum gate process as a base process.

First, as shown in FIG. 1(a)K, the surface of a semiconductor substrate +11 is covered with an oxide film (2) according to a normal manufacturing method, and diffusion windows +31 to +41 for forming sources and drains are opened.

Next, as shown in Figure 1 (b) K'', the source (5) is formed by diffusion.
, a drain (61) is formed and its surface is covered with an oxide film (
Cover with 7). Next, as shown in FIG. 1(c), the oxide film in the gate region is removed and a new gate oxide film (8) is grown.

Up to this point, the manufacturing method for an ordinary aluminum gate has been described.
A polycrystalline silicon layer is grown on the entire surface as shown in FIG. The surface is protected with an oxide film αe. Next, contact holes 111103 at both ends of the resistor and contact holes (13 (14)) for the source and drain are opened as shown in FIG. (
g) As shown in K, a predetermined aluminum wiring α9 is provided to complete the device. In this way, the conventional method was achieved by adding a polycrystalline 7-licon growth step and a photo-etching (P, R) step for forming into a predetermined shape to the base process, so the process As a result, the yield and reliability of the semiconductor devices produced were low.

The object of the present invention is to overcome such drawbacks. It is an object of the present invention to provide a method for manufacturing a semiconductor device having a polycrystalline silicon layer with excellent reliability, which can be obtained without increasing the number of steps.

The present invention focuses on the polycrystalline silicon layer originally used in the silicon gate process, and protects a part of it from becoming conductive due to the addition of impurities, leaving it with high resistance. The basic idea is to form a high-resistance region as a single resistor along with a low-resistance region.

A method for manufacturing a semiconductor device according to the present invention is a method for manufacturing a semiconductor device having a semiconductor substrate, an insulating film covering the substrate, and a polycrystalline silicon conductor layer provided on the insulating film. forming a polycrystalline silicon film on the substrate, covering a predetermined portion of the polycrystalline silicon film with a 7-resist, and then injecting impurities into the poly-7 resist as the photoresist mask. and removing the photoresist.

The present invention is characterized in that the predetermined portion is used as a resistor, and the other portions are used as the polycrystalline silicon film and the conductor layer. In the present invention, a mask for adding the impurity to the polycrystalline silicon is provided. It can be selectively formed on polycrystalline silicon and easily removed after addition for use as a silicon oxide. Also, since the mask is made of 7-otoresist itself, the batting accuracy is good.

Furthermore, in the present invention, since the photoresist is removed and the insulating film is directly coated on the polycrystalline silicon, the surface of the insulating film can be made flat, so that the wiring provided thereon can be raised without being cut off. It can be provided in different densities.

Next, an embodiment of the present invention will be described with reference to FIG. 2 along with its construction method. First, as shown in Figure 2 (a) K.

The surface rfi of the silicon substrate Qυ is covered with field oxidation at(2) according to the usual manufacturing method of the crystal gate MO8, and the gate oxidation a11IJt- is applied to the region where the transistor is to be formed.
Form. Next, as shown in Fig. 2 (CI) K, a round contact hole @ which directly connects the polycrystalline silicon wiring and the diffusion layer
Drill a hole. Next, as shown in Figure 2 (c), % polycrystalline silicon is grown and molded to form a gate electrode (c) and a portion that will become a wiring (c), and a gate oxide film is formed using the electrode (c) as a mask. Portion Q1 to be etched to form source and drain. Drill @. Next, as shown in Figure 2), the part (to) of the polycrystalline silicon wiring (c) that will be the resistor is 7
By performing ion implantation over the entire surface of the substrate covered with photoresist (a), a source (to) and a drain (31) are formed, and at the same time, the gate electrode (25) and wiring (26) are made conductive. Next, as shown in FIG. 2(e)K, the photoresist is removed and the entire surface is covered with a silicon oxide film (32). Next, as shown in Figure 2 (G), the necessary contact holes (33) are drilled, and as shown in Figure 2 (G), the predetermined aluminum wiring (34) is opened.
) to complete the device.

As described above, according to the present invention, by effectively utilizing the polycrystalline layer originally used to form a silicon gate structure, a silicon substrate can be grown without adding a step of growing polycrystalline silicon as a high-resistance layer. At the same time, a high resistance region can be formed. Furthermore, since a photoresist is used as a mask for this purpose, it can be easily applied and removed. Furthermore, since the present invention creates a high resistance as part of the polycrystalline silicon wiring, there is no need for a contact for connection to the wiring. That is, as shown in a partial plan view in FIG. 3(a), in the conventional method, contact holes 01 and 03 are required to connect the specially provided high-resistance silicon (9) and aluminum wiring (c). However, according to the present invention, polycrystalline silicon (
Since a part of c) is left as a high resistance element, no contacts are required, and there is no need to increase the number of contacts, resulting in an excellent yield.

Furthermore, since the 7th photoresist serving as a mask has been removed, the insulating film on the polycrystalline silicon is flat and suitable for a multilayer wiring structure.

Note that the present invention is not limited to the above-mentioned embodiments; for example, the aluminum wiring (34) shown in FIG. Further, by selectively performing impurity diffusion into polycrystalline silicon by changing the concentration, a resistance region having a plurality of 7-t resistances may be formed.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view sequentially illustrating a method for forming a semiconductor device having a high-resistance portion of polycrystalline silicon according to the prior art, and FIG. 2 is a cross-sectional view illustrating a method for forming a semiconductor device according to an embodiment of the present invention. Figure 3 is a plan view explaining how to make contact between the conventional technology and the technology according to the present invention.
Figure 3 (1) is based on the prior art. FIG. 3 (bl is according to the present invention. Reference numbers 1.21 in the figure...semiconductor substrate, 2, 7, 8, 10,
22°23.32...Oxide film, 3,4.27.
“28...window, 11.12, 13.14.24
...Contact hole, 5. “10... Source, 6, 31... Drain, 25...
...Gate substrate, 20...Photoresist, 9.
29...Resistor, 15.34...Aluminum wiring. #1 (Rono no. Iku 53 area (Ino 8th figure (Rono)

Claims (1)

[Claims] In a method for manufacturing a semiconductor device having a semiconductor substrate, an insulating cylindrical film covering the substrate, and a polycrystalline silicon conductor layer provided on the insulating film, the polycrystalline silicon film containing impurities of low lII[ a step of covering a predetermined portion of the polycrystalline 7 silicon film with a 7 photoresist; a step of implanting impurities into the polycrystalline silicon film using the photoresist as a mask; A method for manufacturing a semiconductor device, comprising the step of removing a resist, the predetermined portion being used as a resistor, and the remaining portions being the polycrystalline silicon coating and the conductor layer.