JPH0482222A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent tungsten from coming out on account of temperature change at the time of tungsten growth and heat treatment after growth, by a method wherein protrusions which tungsten has in the horizontal direction are caught in recesses of insulator. CONSTITUTION:In an SiO2 film on a conducting film 3, a hole in which the surface of the conducting film 3 is exposed is formed by a photo mask method and anisotropic dry etching. The whole body is dipped in hydrofluoric acid diluted with water. The dissolving velocity into hydrofluoric acid, of the SiO2 film containing high concentration P is high as compared with the SiO2 film containing little P, so that the SiO2 film containing high concentration P is rapidly dissolved and, recesses are formed. Tungsten 4 of a pillar type is buried in the hole by CVD method. This tungsten 4 generates protrusions 5 in the direction horizontal to the substrate l, in the recesses of the SiO2 film part containing high concentration P in the hole.

Description

[Detailed Description of the Invention] Industrial Application Fields of the Invention The present invention relates to semiconductor devices and methods of manufacturing the same, and also relates to conventional technology.As shown in FIG. To the second insulating film formed on the conductive film 3 There is a method in which a hole is formed in a direction perpendicular to the substrate 1 so that the surface of the conductive film 3 is exposed, and then columnar tungsten 54 is embedded in the hole by the CVD method. However, the problem that this invention attempts to solve is that it has poor adhesion to insulating films such as tungsten gsio2 film and 5isNa film! A very thin natural oxide film is formed on the surface of the conductive film in the hole where tungsten is to be buried, reducing the adhesion to the tungsten. As a result, tungsten peels off from the interface with the conductive film and escapes upward.There is a problem in that the heat treatment temperature cannot be increased. In view of the above, the present invention has been completed.

The purpose of the present invention is to provide a semiconductor device that can prevent peeling by providing protrusions on embedded tungsten wiring, and a method for manufacturing the same. Tungsten is embedded in an insulator in a direction perpendicular to the main surface of the substrate, has protrusions in a direction horizontal to the main surface of the substrate except for the top and bottom, and is in contact with the conductor at the bottom. It has a wiring structure formed by.

Further, as a method for manufacturing a semiconductor device of the present invention, a step of forming a 5102 film containing a high concentration of P (phosphorous) on a first conductor is sandwiched between 5102 films containing almost no P;
A step of forming a hole in the 5102 film containing a high concentration of P and the 5102 film containing almost no P by a photomask method and anisotropic dry etching so that the surface of the conductor is exposed, and then forming a hole to expose the surface of the conductor. immersing in hydrogen acid or diluted hydrofluoric acid to form a depression in the SiO2 portion containing a high concentration of P in the hole;
and a step of filling the hole with tungsten using a VD method to form a wiring.The present invention has the above-described structure, so that the protrusion that the tungsten has in the horizontal direction is caught in the recess of the insulator. However, it is possible to prevent tungsten from escaping upward due to temperature changes and heat treatment during tungsten growth.

FIG. 1 is a partially enlarged view of a wiring part of a semiconductor device according to the present invention.
For example, molybdenum, aluminum, tungsten, tungsten silicide, poly-Si film, etc. may be used.A columnar tungsten 4 having a protrusion 5 in the horizontal direction and having a lowermost portion in contact with the conductive film 3 may be embedded in the insulator 2. FIG. 2 shows the case where the lowest part of the columnar tungsten 4 is in contact with the semiconductor substrate 6 as a conductor instead of the conductive film 3. In FIG. 1 and FIG. The number of protrusions 5 is not limited to two, but it is sufficient to have at least one protrusion. For example, the wiring structure with the configuration shown in Figure 1 can be created as shown in Figures 3 (a) to (d).
In a), on the conductive film 3 of the wiring material formed on the insulating film 2, an SiO2 film 31 containing almost no P, an SiO2 film 32 containing a high concentration of P, an SiO2 film 33 containing almost no P, SiO2 film 3 containing a high concentration of
4. The 5102 film 35 containing almost no P is deposited in this order using, for example, the CVD method.The film thickness of each film is not particularly defined, but is preferably about 10 nm to 11000 nm, and the thickness is preferably 10 nm to 11000 nm. SiO2 film 3 contained in the concentration
It is desirable that the P concentration in the SiO2 films 31, 3 containing almost no P is 10"cm-" or more.
The P concentration of 3.35 is preferably 10"cm-' or less l, 1°. Next, in FIG. 3(b), 5iC on the conductive film 3
Holes 36 are formed in the 12 films 31 to 35 by a photomask method and anisotropic dry etching until the surface of the conductive film 3 is exposed. The shape of the hole 36 as seen from the top ζ Table is preferably square or rectangular t Its size is 0 if the shape is square
．． The desired size is from 2 microns to 10 microns square.C in Figure 3 (c) Soak in hydrofluoric acid or hydrofluoric acid diluted with water. At this time, the dissolution rate for hydrobutic acid is about 1.5 to 10 times faster than the SiO2 film 32.341 containing a high concentration of P-LP and the SiO2 film 31, 33.35 containing almost no LP.
5iOp film containing high concentration of P in 6 32.34
The depressions 37 are formed because of the rapid dissolution of the liquid. SiO2
By selecting the P concentration in the film, as well as the concentration of hydrobutic acid and the diluent, it is possible to control the rate of dissolution in hydrobutic acid, and the depth of the depressions 37 can be varied over a fairly large range. Next, as shown in FIG. 3(d), the columnar tungsten 4 is embedded in the hole 36 by the LCVD method.a When the columnar tungsten 4 is embedded, it may be formed selectively only in the hole 3 or over the entire surface of the substrate. (-The columnar tungsten 4 buried in this way can be formed in the depression 3 in the portion of the Si 02 film 32 and 34 containing a high concentration of P in the hole 36.
7, a protrusion 5 may be formed horizontally with respect to the substrate 1.
In this way, a columnar tungsten wiring structure embedded in an insulator having horizontal protrusions 5 is formed. Fig. 4 shows a partial cross section of a three-dimensional circuit element when the present invention is applied to it. An example of the figure is shown below. The wiring of the first layer transistor 41 is made of a conductive film 3, and the wiring of the second layer transistor 42 is made of a conductive film 43, and the conductive film 3 and the conductive film 43 are connected by a columnar tungsten 4. As explained in detail, according to the present invention, the horizontal protrusions of tungsten are caught in the depressions of the insulator, thereby preventing tungsten from slipping upward due to temperature changes during tungsten growth or subsequent heat treatment. The practical effect is particularly great for semiconductor devices, such as three-dimensional circuit devices, which require high-temperature heat treatment at around 900°C after forming tungsten (-

[Brief explanation of the drawing]

FIG. 1 is a partially enlarged sectional view of a wiring portion of a semiconductor device according to an embodiment of the present invention. FIG. 2 is a partially enlarged sectional view of a wiring portion of a semiconductor device according to an embodiment of the present invention. FIG. 3 is a partially enlarged sectional view of a wiring portion of a semiconductor device according to an embodiment of the present invention. 4 is a cross-sectional view of the process for forming the semiconductor device shown in FIG. 1 according to an example. FIG. 4 is a cross-section when the present invention is applied to a three-dimensional circuit element. FIG. FIG. 1...Substrate, 2...Insulator 3...Conductivity wL
4 columnar tungsten, 5... protrusions 31.33.35
-SiO2K containing almost no P 32.34...
・5iOelf containing a high concentration of P! , 37...Name of Kubomo's agent Patent attorney Shigetaka Awano Haka 1 name 1
Figure 41 Lord Fusyu/Kusuwon 2nd r! ! J Diagram ~ Joichipu Dimension Diagram

Claims (4)

[Claims] (1) It is embedded in an insulator in a direction perpendicular to the main surface of the substrate, and has protrusions in the horizontal direction with respect to the main surface of the substrate except for the top and bottom, and a conductor at the bottom. 1. A semiconductor device characterized by having a wiring structure formed of tungsten in contact with tungsten. (2) A semiconductor device, wherein the conductor according to claim 1 is a conductive film or a semiconductor substrate. (3) SiO containing a high concentration of P (phosphorus) on the conductor
A process of sandwiching the _2 film between two SiO_2 films containing almost no P, and a photomask method and anisotropic dry etching are used to form the SiO_2 film containing a high concentration of P and the SiO_2 film containing almost no P. A step of forming a hole so that the surface of the conductor is exposed, and then immersing it in hydrofluoric acid or diluted hydrofluoric acid to form a depression in the portion of the SiO_2 containing a high concentration of P in the hole portion. A method for manufacturing a semiconductor device, comprising: a step of filling the hole with tungsten using a CVD method to form a wiring. (4) A method for manufacturing a semiconductor device, wherein the conductor according to claim 3 is a conductive film or a semiconductor substrate.