JPH01212439A - Processing of interlayer film - Google Patents

Abstract

PURPOSE:To relax the step difference of the surface of an interlayer film to maintain an evenness and to contrive the improvement of a yield by a method wherein, after an etching is performed on an organic polymeric material layer up to the uppermost end of an insulating material layer, the ratio of the etching rate of the insulating material layer to that of the organic polymeric material layer is specified to dry etching the insulating material layer. CONSTITUTION:An upper organic polymeric material layer 4 and a lower interlayer film 3 are etched back using a reactive ion etching(RIE) method. In this case, at a point of time when the layer 4 is etched to the middle of the layer 4 and the vertex of the film 3 is exposed to the surface, the etching condition of the RIE is set in such a way that the ratio of the etching rate of the film 3 to that of the layer 4 exceeds 1 and reaches a value not exceeding 1.6 and the layer 4 is successively etched until a prescribed time. Thereby, the step difference of the surface of the film 3 is remarkedly reduced to secure an evenness, a processing of wiring layers 2, which are formed on the upper surface of a substrate 1, is facilitated and the improvement of a yield can be contrived.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for processing an interlayer film, and specifically relates to a method for processing a glabella film in a wiring structure as a semiconductor layer, and in particular, It concerns flattening of the glabellar membrane.

[Conventional technology]

Various methods have been proposed for flattening the glabellar film in a wiring structure, and the main ones include (1) glass flow method, (2) bias sputtering method, and (2) etchback method. The glass flow method flattens the unevenness of the wiring layer using fluid glass, but this method requires heating at a high temperature of several hundred degrees in order to release the solvent in the glass, which deteriorates the film quality of the wiring layer. It may cause deterioration. Additionally, cracks may occur in the glass body due to thermal stress. The bias sputtering method for insulating films sputters an insulator while applying bias power to the substrate.The drawbacks of this method are that if too high a bias is applied, there is a risk of degrading device characteristics; The throughput is poor. In addition, the etch-back method removes the convex portion of the insulating film on the wiring film at the same time as etching the resist, and in the conventional technology of this method, the etch rate of the insulator and the resist becomes 1:1 during etching. Since etching is performed under such conditions, the etch rate of the resist varies depending on the exposed area of the insulating film, and as a result, it has often been experienced that sufficient flatness cannot be obtained.

[Problem to be solved by the invention]

If the surface level difference of the glabellar insulating film is large, the step coverage of the wiring layer formed thereon will deteriorate, resulting in disconnection of the wiring layer and lowering the yield.

[Means to solve the problem]

The present invention was made with attention to these problems, and in the process of flattening the glabellar membrane by an etch-back method,
It is an object of the present invention to provide a technique that can reduce the surface level difference of an interlayer film and maintain flatness close to perfect flatness.

In the present invention, when etching back the upper organic polymer material layer and the lower interlayer film using reactive ion etching (RIE), the upper organic polymer material layer is etched halfway and the interlayer film is removed. When the apex is exposed to the surface, the RIE etching conditions are set so that the etch rate ratio of the interlayer film to the organic polymer material layer exceeds 1 and falls within 1.6, and etching is continued for a predetermined time. It is characterized by: In the conventional technique, etching is performed by setting the RIE etching conditions so that the etch rate ratio of the interlayer film to the organic polymer material layer is 1.

〔Example〕

FIGS. 1A, B, and C are cross-sectional views showing process diagrams of an embodiment of the present invention, and the processing method of the present invention will be explained below.

After forming a wiring layer 2 on a substrate 1, an interlayer film 3 is deposited, and an organic polymer material layer 4 is further applied thereon, and this is heat-treated to form a wiring structure having a flat surface. do(
Figure 1A).

Next, the surface of the wiring structure configured in this way is etched by reactive ion etching (RIE),
Continuing etching until the surface of the organic polymer material N4 reaches the top of the glabellar membrane 30 For example, using a normal RIE device, use C) IF310□ mixed gas as the etching gas, flow rate ratio 75/75SCCM, RF power 100. When GW is applied, the etch rate of the organic polymer material layer 4, called 0FPR, is about 850 etchings/m i m. If the film thickness from the top of the interlayer film 3 to the surface of the organic polymer material layer 4 is, for example, lum, the etching time requires about 12 minutes. When the etched surface of the organic polymer layer 4 reaches the top of the interlayer film 3, the RIH etching conditions are changed so that the etching rate of the interlayer film 3 is slightly higher than that of the organic polymer layer 4. (Figure 1B)
That is, CHF310, flow rate 75/40SCCM, RF
When the power is 1250 W and the pressure is 50 mTorr, the etch rate of the glabellar membrane and the organic polymer material layer is 4001, respectively.
360 people/mim. When observing the level difference on the surface of the glabellar membrane 3 after etching the glabellar membrane 3 by 0.8 μm from its apex under such etching conditions, it was found that the level difference was considerably reduced (first Figure C)
.

Therefore, the surface step of the interlayer film before etching is A, and the surface step of the interlayer film after etching by the method described above is B.
If the surface flattening rate α is defined as α=1-B/A and the relationship between α and the etch rate ratio R of the interlayer film 3 to the organic polymer material WJ4 is determined, the result will be as shown in Figure 2. . That is, when R is in the range of 1.1 to 1.4, α shows a value of approximately 0.9, and it is clear that the surface of the interlayer film is relaxed to a level close to completely flattened.

Under the etching condition of R=1, α is 0.8 or less, and the level difference on one surface is relatively large. For practical use, α should be 0.
It is considered that 8 or more is necessary. Therefore, etching the glabellar membrane 3 and the organic polymer material layer 4 under conditions such that R exceeds 1 and falls within 1.6 is effective for flat chlorination.

〔Effect of the invention〕

As explained above, 1. In the process of simultaneously etching the glabellar membrane and the organic polymer material layer, the RIB etching conditions are adjusted so that the etch rate ratio of the glabellar membrane/organic polymer material layer is greater than 1 or less than 1.6. Set,
By etching, it is possible to significantly reduce the level difference on the surface of the interlayer film and ensure flatness, thereby facilitating the processing of the wiring layer formed in the upper layer and improving the manufacturing yield of LSI.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the steps of an embodiment of the present invention, and FIG. 2 shows the relationship between the etch rate ratio R of the glabellar film to the organic polymer material layer and the surface flattening rate α. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Wiring layer, 3... Interlayer film, 4...
...Organic polymer material layer Fig. 1 is a sectional view showing the steps of an embodiment of the present invention.

Claims (1)

[Claims] An insulating material layer is formed on a substrate having a wiring layer, and further,
In the step of forming an organic polymer material layer thereon and the step of dry etching the organic polymer material layer and the insulating material layer, after etching the organic polymer material layer to the top of the insulating material layer, A method for processing an interlayer film, comprising dry etching the insulating material layer under etching conditions such that the etch rate ratio of the insulating material to the organic polymer material exceeds 1 and falls within 1.6.