JPS618953A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To decrease the difference in steps only by the simple change in processes and by the change in conditions without using silica or a new material such as high viscosity macromelecular material, by using anisotropic etching, and making a thin film to remain around the difference in steps. CONSTITUTION:An insulating film 5 is laminated so as to cover a wiring 1, which is extended on an insulating film of a semiconductor wafer. The thickness of the insulating film 5 in the direction perpendicular to the wafer around the difference in steps is shown by a numeral 6. The thickness of the film at a flat part in the direction perpendicular to the wafer is shown by a numeral 7. The width 7 is thinner than the thickness 6. Anisotropic etching having the etching characteristic perpendicular to the wafer is performed for the wafer by the etching amount of the thickness 6 or less, under the condition the etching rate of the insulating film is higher than a wiring material 1. Then, a part 8 of the insulating film 5 remains around the difference in steps. Thereafter, another insulating film 9 is formed, and a sputtered or evaporated metal 10 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical field to which the invention pertains The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a method for manufacturing a semiconductor device that improves the coverage of a subsequently laminated film for steep steps such as wiring. .

(2) Description of the Prior Art As various materials are stacked on top of the steps on the wafer surface, the coverage gradually deteriorates.

This tendency is particularly noticeable for metals grown by vapor deposition or sputtering. FIG. 1 shows an example of this. An insulating layer 2 grown by CVD, which is said to have good coverage, is provided on the wiring 1, and a metal 3 grown by vapor deposition or the like used for the upper wiring is formed thereon. In this case, the portion 4 becomes extremely thin, which may cause a break in the wiring formed using the second layer of metal 3.

As a method to improve this, there is a method in which silica or a high viscosity polymeric material is applied after forming one level difference to smoothen the level difference and improve coverage.

However, with this method, it is necessary to prepare new materials and new equipment, and it is also necessary to check the effects on semiconductor devices made of new materials, which has the disadvantage that it cannot be implemented with simple process changes and condition changes. .

(3) Detailed Description of the Invention The purpose of the present invention is to smooth out steep steps caused by wiring without using new materials, and to change the metal coverage layered on top by simply changing the process and changing two conditions. An object of the present invention is to provide a method for manufacturing a semiconductor device that can be performed.

(4) Structure of the Invention The present invention grows an insulating film over the entire surface of a wiring that has a steep step, and uses anisotropic etching that can be etched perpendicularly to the wafer. By leaving the insulating film only around the steps and making the steps gentle, the coverage is improved for the thin film laminated on top. , Cv, which has been conventionally used without using polymeric materials.
The insulating film obtained by D-growth etc. can be used as it is to reduce the step difference, and the coverage of the thin films to be laminated can be improved by a simple process change and two condition changes.

(5) Explanation of the principle and operation of the invention A thin film is grown to cover a steep step, and then the entire surface of the wafer is etched using anisotropic etching, which has etching characteristics perpendicular to the wafer surface. The thickness of the film in the vertical direction of the wafer on the side surface of the step is thicker than on other parts, so by adjusting the etching time, it is possible to leave a thin film only around the step. can be made gentler.

(6) Detailed Description of the Invention Next, referring to the step drawings in order regarding the embodiments of the present invention,
explain.

First, referring to FIG. 2, the insulating film 5 is laminated to cover the wiring M1 extending over the insulating film on the semiconductor wafer. Here, the thickness in the direction perpendicular to the wafer around the insulating film 50 step difference is indicated by 6, and the thickness in the direction perpendicular to the wafer at the flat portion is indicated by 7. Here, since 7 is thinner than 6, anisotropic etching with a 12-chip characteristic perpendicular to 8...- is performed on this wafer for interconnects with an etch rate of 1 for the insulating film. If etching is performed to a thickness of 6 or less under conditions higher than the material, the result will be as shown in Fig. 3. In Fig. 3, a portion 8 of the insulating film 5 remains around the step. Then, as shown in FIG. 5, a sputtered or vapor deposited metal 10 is formed.

Comparing FIG. 1 with FIG. 5, it can be seen that the portion 8 has an effect of reducing the level difference, and the structure of FIG. 5 can significantly improve the coverage. At this time, if the material of the portion 8 formed by the insulating film 5 is the same as that of the insulating film 9, it will appear as if the coverage of the insulating film 9 has simply changed, and there is no need to confirm the reliability of the material. Easy to apply to manufacturing processes.

Figure 6 shows a further development of the present invention, in which, after reaching the state shown in Figure 3, another insulating film is grown over the entire surface as in Figure 2, and that insulating film is left around the step. 11 is the remainder of the insulating film. By doing this, a greater level difference reduction effect can be expected compared to that shown in FIG. 3, and by repeating the same process, the level sloping state can be changed as necessary.

(7) Detailed description of the invention As explained above, the present invention uses anisotropic etching to leave a thin film only around the steps, thereby eliminating the need for new materials such as silica or high-viscosity polymer materials. It is effective to reduce the difference in level with only 9 simple process changes and condition changes.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the state of laminated thin films when no step reduction method is used. 2 to 5 are cross-sectional views showing the first embodiment of the present invention, and FIG. 3 shows an insulating film on the surface of FIG. 2 by anisotropic etching, only around the steps. Fig. 4 is a cross-sectional view of an insulating film laminated on the surface of Fig. 3, and Fig. 5 is a cross-sectional view of a stepped surface in which a metal with poor coverage is laminated on the surface of Fig. 4. It is a diagram. FIG. 6 shows a second embodiment of the present invention. After the stepped portion is created as shown in FIG. 3, an insulating film is further grown and anisotropically etched so that it remains only around the stepped portion. FIG. 3 is an etched cross-sectional view. In addition, in the figure, 1... Wiring with steep steps,
2°゛°°°・An insulating film grown by CVD or the like with good coverage covering 1, 3... A metal film such as a vapor deposited film with poor coverage laminated on top of 2, 4...
...3 is a part that is extremely thin due to the shadow of the step, 5...is an insulating film grown by CVD with good coverage covering 1, 6... is the area around the step 1 5 height in the direction perpendicular to the wafer at
The portion of the insulating film 5 remaining only around the step, 9...
・Good coverage covering 1 and 8 (insulating film by VD growth, 10...Metal film such as vapor deposited film with poor coverage laminated on top of 9, 11... After the steps are formed as shown in Figure 3, another absolute MjR film is grown and anisotropically etched, and this is the part of the other insulating film that remains around the steps 1 and 8. 2 figures, 1,000 figures, 3 figures

Claims (1)

[Claims] After the wiring pattern of a semiconductor device is formed, an insulating film is formed on the entire surface, and the entire surface is etched using anisotropic etching that proceeds perpendicular to the wafer, leaving an insulating film around the wiring pattern, and then other layers are etched on top of it. 1. A method for manufacturing a semiconductor device, comprising the step of growing an insulating film.