JPH01222461A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To make possible the prevention of the disconnection of wirings, a reduction in resistance and the prevention of a leakage current without forming a step part by a method wherein an impurity is selectively implanted in a non-doped Si layer to form the wirings and resistance parts and the wirings are not etched and are each formed into a multilayer interconnection as they are flat. CONSTITUTION:An insulating film 2 is formed on a semiconductor substrate 1. Then, an undoped Si layer 3 is formed on the film 2 by a CVD method. Phosphorus is ion-implanted in wirings 6 and regions for forming resistance parts using a photoresist as a mask. Then, an Al layer 10 is formed on the whole surface of the substrate. Moreover, the layer 10 is selectively left by a lift-off method and after oxygen is ion-implanted using the left layer 10 as a mask, the layer 10 is removed by fusion. Then, an Si oxide layer 11 is formed by heattreating and this is used as an insulating layer. Then, an insulating film 7 is formed on the wirings 6 and the layer 11. Thereby, as no step part is formed, a leakage current can be reduced and furthermore, the wirings are formed in the shortest distance and moreover, it becomes possible that the wirings are not disconnected.

Description

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

[Conventional technology]

In recent years, as semiconductor chips have become more integrated, problems such as disconnections in multilayer wiring structures and leakage current between wirings have become a problem.

FIGS. 2(a) to 2(d) are cross-sectional views of a semiconductor chip shown in order of steps for explaining an example of a conventional method of manufacturing a semiconductor device.

As shown in FIG. 2(a), an insulating film 2 is formed on a semiconductor substrate 1.
Next, an undoped silicon layer 3 is formed on the insulator 1112 by the CVD method.6 Next, as shown in FIG. 2(b), phosphorus is ion-implanted into the undoped silicon layer 3. , to a predetermined resistance value.

Next, as shown in Figure 2(c), by photolithography,
A portion that will become the wiring 6 and the resistance section is formed.

Next, as shown in FIG. 2(d), an insulation II 7 is formed on the insulation film 2, the wiring 6 and the resistor part, and an aluminum wiring 8 is further formed to form a multilayer wiring, thereby forming a semiconductor device. It was.

[Problem to be solved by the invention]

In the conventional semiconductor device manufacturing method described above, when forming a multilayer wiring, as shown in FIG. 2(d), the insulating layer 17
Also, a stepped portion is generated in the upper layer wiring 8.

Insulated IF! The film thickness of 7 becomes thinner,
This becomes a cause of leakage current between the lower layer wiring 6 and the resistor section and the upper layer wiring 8.

In addition, since the upper rtη wiring 8 passes through a step, there is a possibility of disconnection at that part, and the wiring distance becomes longer, which increases the wiring resistance. An object of the present invention is to provide a method for manufacturing a semiconductor device that can prevent step portions from forming multilayer wiring, reduce wiring breakage, reduce wiring resistance, and prevent leakage current.

[Means to solve the problem]

The method for manufacturing a semiconductor device of the present invention includes the steps of forming an insulating film on a semiconductor substrate, forming an undoped silicon layer on the insulating film, and selectively implanting impurities into the undoped silicon layer. The method includes a step of forming wiring and a resistor, a step of implanting oxygen into the undoped silicon layer other than the wiring and the resistor, and a step of bonding oxygen and silicon by heat treatment.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1A to 1E are cross-sectional views of a semiconductor chip shown in order of steps for explaining an embodiment of the present invention.

As shown in FIG. 1(a), an insulating film 2 is formed on a semiconductor substrate 1.
form. Next, an undoped silicon layer 3 is formed on the insulating film 2 by the CVD method.

Next, as shown in FIG. 1(b), using a photoresist as a mask, phosphorus ions are implanted into the region where the wiring 6 and the resistance portion are to be formed.

Next, as shown in FIG. 1(c), an aluminum layer 10 is formed over the entire surface of the substrate.

Next, as shown in FIG. 1(d), the aluminum layer 10 is selectively left by a lift-off method, and using this as a mask, oxygen ions are implanted. Thereafter, a silicon oxide layer 11 is formed by performing a heat treatment to dissolve and remove the aluminum layer 10, and this is used as an insulating layer.

Next, as shown in FIG. 1(e), an insulating film 7 is formed on the wiring 6 and the silicon oxide layer 11. At this time, since the wiring 6 and the silicon oxide layer 11 are flat, the insulating film 7 does not form a stepped portion. Next, aluminum wiring 8 is formed on the insulating film 7 to form a multilayer wiring.

In the semiconductor device formed in this example, since no stepped portion is formed, a thin portion is not formed in the insulating film formed as an upper layer, and leakage current can be reduced, and the wiring distance is the shortest. This makes it possible to avoid disconnection.

In this example, phosphorus was used as an impurity, but the same effect can be obtained using boron.

〔Effect of the invention〕

As explained above, in the present invention, impurities are selectively implanted into an undoped silicon layer to form wiring and a resistor part, and an insulating film and upper layer wiring are formed on the top surface of the undoped silicon layer while the silicon layer remains flat without etching. Since multilayer wiring is formed, no step portions are formed, and it is possible to prevent wiring breakage, reduce wiring resistance, and prevent leakage current.

[Brief explanation of the drawing]

1(a) to 1(e) are cross-sectional views of a semiconductor chip shown in the order of steps for explaining one embodiment of the present invention, and FIG. 2(a)
) to (d) are cross-sectional views of a semiconductor chip shown in the order of steps for explaining an example of a conventional method for manufacturing a semiconductor device. 1... Semiconductor substrate, 2... Insulating film, 3
......Undoped silicon layer, 4... Photoresist film, 6... Wiring, 7... Insulating film, 8... Aluminum wiring, 10...
- Aluminum layer, 11...Silicon oxide layer.

Claims (1)

[Claims] a step of forming an insulating film on a semiconductor substrate, a step of forming an undoped silicon layer on the insulating film, a step of selectively implanting impurities into the undoped silicon layer to form a wiring and a resistance part, A method for manufacturing a semiconductor device, comprising the steps of: implanting oxygen into the undoped silicon layer other than the wiring and the resistor portion; and performing heat treatment to bond oxygen and silicon.