JPS62128116A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To realize formation of a contact part in a small area, by irradiating a part of an oxide film with ions having much reducibility and having it get conductivity by reduction so that reliability of electrical contact is improved between an upper wiring and a lower silicon substrate. CONSTITUTION:After a silicon oxidizing film 2 is formed with thickness of 1mum or so on a silicon substrate 1, H<+>2 ion beams 5 or the like are implanted with a dose amount of 10<18>ps/cm<3> or less and acceleration voltage of 20kV or so within about 1X1mum<2> area of a place in which a contact part 3 is to be formed. Thereafter, an upper wiring 4 is formed on the oxidizing film 2. Ion implantation may be performed at the contact part by an implantation process such as a general phototype process and a nonfocussed ion beam implantation process. Any material is available for an oxidizing film used as a layer insulating film, if the material oxidized by it has conductivity. Besides, any ion is available for a kind of an implanting ion as long as it has reducibility. Particularly, CO<+> ion beams are preferable because it can be changed into volatile CO2 by a reducing reaction.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device, and more particularly to electrical contact between wiring in an upper layer and a silicon substrate in a lower layer via an interlayer insulating film. It is something.

[Conventional technology]

FIG. 2 +a) to fcl are cross-sectional views showing sequential steps in a conventional semiconductor device manufacturing method;
1) is a silicon substrate, (2) is a silicon oxide film as an interlayer insulating film formed on the silicon substrate (1), (3)
(4) is the contact hole drilled in the oxide film (2), and (4) is the upper layer wiring (wiring (4)) deposited by vapor deposition or thin film on the upper surface of the oxide film (2) including the contact hole (3). (includes the electrode part; the same applies hereafter).

Next, the process will be explained. Figure 2 shows a fat layer on the silicon substrate (1) after the process of forming the source and drain.
An oxide film (2) is deposited to a thickness of 1 μm as shown in FIG.

Subsequently, a photoresist is applied to the oxide film (2), exposed to ultraviolet light, and developed, after which a pattern of contact holes of about 2×2 μm 2 is formed. After that, the oxide film (2) is
Dry etching is performed with Fx gas to form a contact hole (3) as shown in FIG.
j! A Si alloy is sputter-deposited, and an upper layer wiring (4) is formed as shown in FIG. 2 fcl by a photolithography process and an etching process. is constructed as described above, so the size of the contact hole (3) is 2 x 2 μm2.
As shown in Fig. 3 ta+, sputter-bound A6 or Aj! The Si alloy is deposited gently to the bottom of the contact hole (3), and sufficient electrical contact can be made between the upper wiring (4) and the lower silicon substrate (1). However, IMD-RAM, which is currently being prototyped as a microscopic device, and 4 which are expected to appear in a few years.
In MD-RAMs and the like, the size of the contact hole (3) will be further miniaturized, and in the latter case in particular, it is expected that the size will be about 1-x1 μm2. When the size of the contact hole (3) is about 1 x 1 μm2, the upper layer wiring (4) cannot be sufficiently formed in the contact hole (3) using the conventional manufacturing method, as shown in Figure 3(b). , upper management* f41
The electrical contact between the silicon substrate (1) and the silicon substrate (1) may deteriorate, resulting in high resistance or disconnection. To solve this problem, taper etching methods and various contact hole flattening techniques have been proposed, but there is still no definitive solution.

This invention was made to solve the above-mentioned problems, and provides a semiconductor device that can maintain good electrical contact between the upper wiring and the lower silicon substrate even if the contact hole is miniaturized. The purpose is to obtain a manufacturing method for.

Another object of the present invention is to provide a method for manufacturing a semiconductor device that can maintain good conductivity in a contact area by removing compounds generated by the combination of oxygen and ions in an oxide film. shall be.

[Means for solving problems]

The method for manufacturing a semiconductor device according to the present invention involves implanting strongly reducing ions into the part of the oxide film that is the glabella insulating film where the contact hole should be, reducing the oxide film in the part that should become the contact hole and making it conductive. The method for manufacturing a semiconductor device according to another aspect of the present invention further provides an electrical contact between the upper layer wiring and the lower layer silicon substrate by imparting properties to the oxide film. It is designed to remove compounds produced by the combination of oxygen and ions.

[Effect]

In the step of irradiating highly reducing ions in the present invention, the oxide film in the contact portion is reduced to have conductivity, and the upper layer wiring and the lower layer silicon substrate are brought into electrical contact. That is, the present invention utilizes the fact that when strongly reducing ions are implanted into an oxide, a portion of the oxide is reduced according to the following reaction formula. In addition, M, O, are oxides,
I is the implanted ion, m, n and p are the valence numbers.

MIIOII+pInM+1. Therefore, if the substance M has conductivity, a part of the oxide can be made conductive by implanting ions and performing reduction.

Further, the compound removal step in another aspect of the present invention prevents impurities from remaining in the contact portion and maintains good conductivity of the contact portion.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. M1
In the figure, (1) is a silicon substrate, (2) is a silicon oxide film, (3) is a contact part, (4) is an upper layer wiring,
(5) is a highly reducing hydrogen ion beam.

Next, the process will be explained. As shown in Figure 1 (al), a silicon oxide film (2) of 1μ
After forming the contact portion (3) to a thickness of 1.0 m, as shown in FIG.
The implantation is performed at a dose of I'1/Cm" or less.

Thereafter, as shown in Figure tc+, an upper layer wiring (4) is formed on the oxide film (2).

When the reliability of the semiconductor device was measured after completion, it was confirmed that the reliability was much improved compared to when contact holes of 1×1 μm 2 were formed using the conventional method.

In this embodiment, a field ionization type gas ion source was used for the ion implantation process, but ions may be implanted into the contact portion by a general photolithography process and an implantation process using a non-focused ion beam.

Moreover, any oxide film used as the interlayer insulating film may be used as long as the substance to be oxidized has conductivity. If a compound produced by the reaction of oxygen and ions in the oxide film inhibits good conductivity of the contact portion, it is desirable to perform a step of removing this compound after the ion irradiation step.

In addition, any ion species to be implanted may be used as long as it has reducing power, but Co1 ion beams in particular become volatile CO□ after undergoing a reduction reaction, so they do not leave impurities in the contact area and are more suitable as ion beams. There is.

〔Effect of the invention〕

As described above, according to the present invention, a part of the oxide film is reduced to make it conductive and this part is used as a contact part, so the upper layer wiring is almost flat compared to the conventional semiconductor device manufacturing method. Electrical contact can be made with the silicon substrate through the contact portion, which has the effect of providing highly reliable electrical contact between the upper wiring and the lower silicon substrate. Furthermore, it is possible to form a contact portion with a much smaller area than in the conventional method, and the manufacturing process is also much simpler than in the conventional method.

Further, according to another aspect of the present invention, compounds generated in the oxide film as a result of ion irradiation are further removed, so that good conductivity of the contact portion can be maintained.

[Brief explanation of drawings]

FIG. 1 (al~(cl) is a cross-sectional view showing the sequential steps in the method for manufacturing a semiconductor device according to an embodiment of the present invention, and FIG. The cross-sectional view shown in FIG. 3(a) shows that the size of the contact hole is 2×2 μm according to the conventional semiconductor device manufacturing method.
Fig. 3 is a cross-sectional view when the size of the contact hole is approximately 1 x 1 μm (bl is 1 x 1 μm).
FIG. (1) is a silicon substrate, (2) is an oxide film, (3) is a contact portion, (4) is an upper layer wiring, and (5) is a hydrogen ion beam. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (6)

[Claims] (1) A step of forming an oxide film on a silicon substrate, and irradiating a portion of the oxide film where a contact hole is to be formed with ions with strong reducing power to reduce a part of the oxide film to form a contact portion. A method for manufacturing a semiconductor device, comprising the steps of: forming an upper layer wiring on the oxide film including the contact portion. (2) A step of forming an oxide film on the silicon substrate, and irradiating a portion of the oxide film where a contact hole is to be formed with ions with strong reducing power to reduce a part of the oxide film to form a contact part. a step of removing a compound in which oxygen and the ion are bonded in the oxide film; and a step of forming an upper wiring on the oxide film including the contact portion. Method of manufacturing the device. (3) The method for manufacturing a semiconductor device according to claim 1 or 2, characterized in that hydrogen ions are used as the ions with strong reducing power. (4) The method for manufacturing a semiconductor device according to claim 1 or 2, characterized in that carbon monoxide ions are used as the ions with strong reducing power. (5) The method for manufacturing a semiconductor device according to claim 1 or 2, wherein silicon dioxide is used as the oxide film to which the ions are irradiated. (6) A method for manufacturing a semiconductor device according to claim 1 or 2, characterized in that a field ionization type gas ion source is used as the ion source for irradiating the ions.