JPH0366119A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form with high accuracy a multilayer resin film pattern which has few defects by restricting the remaining film thickness of a lower organic resin film and determining the film thickness of an upper organic resin film while joining its upper film with the lower film when the surface of an intermediate metallic resin film pattern is exposed to the outside in the process of dry- etching of the lower organic resin film after making patterns of the upper organic resin film and the intermediate metallic resin film act as masks. CONSTITUTION:A lower resist film 3 is etched by employing patterns 5' and 4' of an upper resist film and an intermediate SOG film as masks and applying an RIE process in which a CF4 gas is used instead of an O2 gas. In such an etching process, even an upper resist film pattern 5' is etched simultaneously and when the surface of the intermediate SOG film pattern 4' is exposed, the residual film thickness of the lower resist film 3 comes to 1.0mum. Subsequently, when the residual film thickness (h) of the resist film 3 is etched by making the above SOG film pattern 4' to act as a mask, a lower resist film pattern 3' is formed. Since the remaining film thickness of the above film 3 does not exceed 1.0mum, occurrence of defects in the pattern is suppressed to a minimum.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a method for forming a multilayer resin film pattern, and aims to form a multilayer resin film pattern with few defects with high precision. A resin film, an intermediate layer metal resin film, and an upper layer organic resin film are sequentially formed, and then an upper layer organic resin film pattern is formed by photolithography, and then dry etching is performed using the upper layer organic resin film pattern as a mask to form an intermediate layer metal resin film. A pattern is formed, and then dry etching is performed using the upper organic resin film pattern and the intermediate metal resin film pattern as masks to form a lower organic resin IlΔ pattern, and the thin film is etched using the lower organic resin pattern as a mask. A method for manufacturing a semiconductor device comprising the step of dry etching the lower organic resin film using the upper organic resin film pattern and the intermediate metal resin film pattern as masks, in which the upper organic resin film pattern is etched. The thickness of the upper organic resin film is set so that when the surface of the intermediate metal resin film pattern is exposed after removal, the remaining thickness of the lower organic resin film does not exceed 1 μm.

[Industrial application field]

The present invention relates to a method for forming a multilayer resin film pattern, and more particularly to a method for forming a multilayer resist film pattern.

Since there are usually irregularities on a substrate on which a semiconductor element is to be formed, the thickness of a resist formed directly on the irregularities becomes non-uniform. Therefore, in normal photolithography, overexposure and underexposure occur, making it impossible to obtain a highly accurate resist pattern. The multilayer resist pattern forming method is a method used to avoid such problems, and is suitable for patterning high-density ICs because pattern accuracy can be maintained regardless of the pH convexity of the substrate. However, since the formation process is complicated, defects are likely to occur in the pattern, and improvements are desired.

[Conventional technology]

FIG. 5 is a cross-sectional view for explaining a pattern forming process using a conventional multilayer resist. As shown in FIG. 2A, a thin film to be patterned, for example, a front film 2, is formed on a semiconductor substrate 1, and a lower resist film 3 made of an organic resin is first applied thereon. The unevenness (not shown) existing on the surface of the thin film 2 is flattened by making the lower resist film 3 sufficiently thick. Next, on this flattened lower resist film 3, a thin and uniform intermediate layer SOG (spin-on glass) film 4 made of a metal resin film and an upper resist film 5 made of an organic resin are sequentially applied. Then the same figure (b)
As shown in FIG. 2, an upper resist film pattern 5' is formed by ordinary photolithography.

By making the upper resist film 5 thin and uniform in thickness as described above, highly accurate patterning is possible. Next, as shown in FIG. 5C, using the upper resist film pattern 5' as a mask, reactive ion etching (RIE) is performed by flowing 02 gas to form an intermediate SOG film pattern 4'. Next, the lower resist film 3 is etched by RIE using the upper resist film pattern 5' and the intermediate SOG film pattern 4' as masks and flowing a fluorine gas.

In the above etching step, since the upper resist film 5 and the lower resist film 3 are the same type of organic resin films containing C and H, there is no etching selectivity. Furthermore, in order to improve pattern accuracy, the thickness of the upper resist film pattern 5' is usually set to be much thinner than the thickness of the lower resist film 3, as described above. Therefore, when the upper resist film pattern 5' is etched away and the surface of the intermediate SOG film pattern 4' is exposed, as shown in FIG. , there will be a thickness.

Thereafter, by etching the lower resist film to a thickness of 11 using the intermediate layer 5 OGI model pattern 4' as a mask, a lower resist film pattern 3' is formed as shown in FIG. 3(e). Thereafter, the AI film 2 is etched using the lower resist film pattern 3' as a mask.

[Problem to be solved by the invention] However, when the above method is actually used, the problem shown in Fig. 5 (
As shown in e), residues 7 of the upper and lower resist films are observed on the AI film. The reason for this is thought to be as follows. That is, as shown in FIG. 5(d), the intermediate layer SOG
RI the lower resist film 3 using the film pattern 4' as a mask.
When etching using the E method, ions in the plasma are accelerated toward the substrate by the self-bias that exists on the substrate side, and Si or Si oxide in the intermediate layer SOG film made of metal resin is sputtered, resulting in SOG
The film residue 6 adheres to the surface of the lower resist nM3 during etching, and this serves as a mask, leaving a residue 7 of the lower resist film. Such residue functions as an etching mask for the layer 119 when patterning the ^1 film 2 using the lower resist film pattern 3' as a mask, resulting in defects in the A1 film pattern.

In order to reduce the pattern defects described above, it is necessary to lower the self-bias on the substrate side to prevent the intermediate layer SOG film from being sputtered, or to prevent the surface of the intermediate layer SOG film pattern 4' from being exposed. The thickness of the upper resist film 5 may be increased as shown in FIG. On the other hand, as stated above, in order to accurately pattern the two-layer resist film 5 by ordinary photolithography, it is necessary to make the film thickness as thin as possible. In other words, reducing pattern defects and improving patterning accuracy impose contradictory conditions on the thickness of the upper resist film, but conventionally the thickness of the upper resist film has been determined empirically. was not optimized.

Therefore, an object of the present invention is to provide a method for forming a highly accurate multilayer resin film pattern with few Bakun defects.

[Means to solve the problem]

The above problem can be solved by sequentially forming a lower organic resin film, an intermediate metal resin film, and an upper organic resin film on a substrate on which a thin film has been formed, and then forming an upper organic resin film pattern by photolithography. Dry etching is performed using the organic resin film pattern as a mask to form an intermediate layer metal resin film pattern, and then dry etching is performed using the upper layer organic resin film pattern and the intermediate layer metal resin film pattern as masks.
A method for manufacturing a semiconductor device comprising the steps of notching to form a lower organic resin film pattern, and etching the thin film using the lower organic resin film pattern as a mask, the method comprising: forming a lower organic resin film pattern using the upper organic resin film pattern and the intermediate metal resin layer; In the process of dry etching the lower organic resin film using the film pattern as a mask, when the upper organic resin film pattern is etched away and the surface of the intermediate metal resin film pattern is exposed, the remaining film thickness of the lower organic resin film is A method for manufacturing a semiconductor device, characterized in that the thickness of the upper organic resin film is set so that the film thickness does not exceed 1 μm, or a lower organic resin film is formed on a substrate on which a thin film is formed, or an intermediate metal resin film is formed on the substrate. A film and an upper organic resin film are sequentially formed, then an upper organic resin film pattern is formed by photolithography, and then dry etching is performed using the upper organic resin film pattern as a mask to form an intermediate metal resin film pattern. A lower layer organic resin film pattern is formed by performing reactive ion etching using the upper layer organic resin film pattern and the intermediate layer metal resin film pattern as masks and applying a magnetic field, or alternatively, the upper layer organic resin film pattern and the intermediate layer metal resin film pattern are etched. After dry etching is performed using the film pattern as a mask to remove the upper organic resin film pattern and expose the surface of the intermediate metal resin film button, reactive ion etching is performed with a magnetic field applied to remove the lower organic resin film pattern. This is achieved by a method of manufacturing a semiconductor device characterized by comprising the steps of: forming a thin film (2) using the lower organic resin film pattern (3') as a mask; and etching the thin film (2).

[For production]

As shown in FIG. 5(d), the cause of defects in the pattern is the intermediate layer SOG film pattern 4' made of metal resin.
This is due to sputtering and the residue 6 adhering to the remaining thickness of the lower resist film 3 made of organic resin. Therefore, it is considered that the thinner the remaining film thickness of the lower resist film is, the shorter the sputtering time for the intermediate SOG film is, and the less the residue is. The inventor conducted an experiment to determine how the residual density of the intermediate layer SOG film changes with respect to the remaining film thickness of the lower resist layer 3, and as a result, data as shown in FIG. 2 was obtained. The figure shows that when the remaining thickness of the lower resist film exceeds 1 pI11 or more, the residual density of the intermediate SOG film increases rapidly.

From the above, the remaining film thickness of the lower resist film is 11 m.
It can be seen that by setting the thickness of the upper resist film so as not to exceed , it is possible to reduce the pattern defect density, and at the same time, it is possible to minimize deterioration in pattern accuracy.

Furthermore, the inventors have discovered that when etching the intermediate layer SOG film by the RIE method, by applying a magnetic field, the residual density of the intermediate layer metal resin film is reduced, and as a result, the pattern defect density is reduced.

Figure 3 shows an RI with a magnet for applying a magnetic field.
This is a cross-sectional view of the main parts of apparatus B, in which 11 is a magnet, 12 is a high frequency electrode, 13 is a ground electrode, 14 is a substrate to be etched, and 15 is a high frequency power source. The figure shows high frequency electrode 1.
2 shows the potential distribution between the electrodes when plasma is generated between the substrate 14 and the ground electrode 13, and a self-bias indicated by V in the figure is applied to the substrate 14. In Figure 4, the above R
High frequency power with a frequency of 13°56 MHz is applied to the IE device.
This figure shows the magnetic field dependence of the self-bias applied to the substrate 14 when 0 W is applied. As is clear from the figure, the self-bias is reduced by applying a magnetic field of 1 2 .

In other words, the application of a magnetic field is effective in preventing ions in the plasma from being accelerated toward the substrate, impacting the intermediate layer SOG film pattern, and scattering onto the remaining thickness of the underlying resist film, thereby preventing the ions in the intermediate layer 5OG19 from being scattered. Density can be reduced.

Such a phenomenon also occurs when a metal resin film other than the SOG film is used.

〔Example〕

FIG. 1 is a process sectional view showing an embodiment of the present invention.

As shown in FIG. 5A, an AI film 2 is formed on a semiconductor substrate l, a novolak positive resist film 3 is used as a lower resist film 3 made of an organic resin, and a novolac positive type resist is applied to a thickness of 2 μm, and an intermediate SOG film 4 made of a metal resin is formed. (For example, Tokyo Ohka OCD t
Vpe 2) was 0.37ffi, and novolac positive type resist was used as the upper resist film 5 made of organic resin.
．． 57+m, applied sequentially. Then, as shown in FIG. 2B, an upper resist film pattern 5' is formed by ordinary photolithography. Next, as shown in the same figure (C), 1. RI is performed using the upper resist film pattern 5' as a mask.
Etching is performed using the E method to form an intermediate layer SOG film pattern 4'. The above etching uses 02 gas to 3003
CCM flow, pressure 0°03 Torr, frequency 1
This was done by applying 200 W of RF power at 3.56 MHz. In this etching process, etching of the upper resist film 5 also progressed, and as a result, the film thickness of the upper resist film pattern 5' became 1.0-. Next, using the upper resist film pattern 5' and the middle 1soc film pattern 4' as masks, the lower resist film 3 was etched by RIE using CF gas instead of 02 gas.

In this etching process, the upper resist film pattern 5' is also etched at the same time, and when the surface of the intermediate SOG film pattern 4' is exposed, the remaining film thickness of the lower resist film 1li3 is 1.07 zm, as shown in FIG. It became.

Further, by etching the remaining thickness of the lower resist film 3 using the intermediate layer SOG film pattern 4' as a mask, a lower 34-layer resist film pattern 3' is formed as shown in FIG. Ru.

In the above embodiment, when etching the lower layer resist 1 to film 3 using the intermediate layer SOG film pattern 4' as a mask, the remaining film thickness of the lower layer resist 1 to film 3 does not exceed 1.0 μm. As is clear from the figure, pattern defects can be minimized.

Also, when etching the lower resist film 3 by RIE using the intermediate layer SOG film pattern 4' as a mask, the third
When a magnetic field of 100 Gauss is applied using an RIE device (not shown), the self-bias applied to the substrate decreases from 500 V to approximately 100 V as shown in Figure 4, and as a result, the residual density of the intermediate SOG film decreases. was able to be significantly reduced compared to conventional methods.

According to this method, the remaining film thickness of the lower resist film 3 is 1.
Even if it exceeds 0 μm, the residual density of the intermediate layer SOG film can be reduced to an extent that does not cause any practical problems. - can. Furthermore, etching with the application of a magnetic field can also be used from the stage of forming the lower resist film 3 using the upper resist film pattern 5' and the intermediate S○G film pattern 4' as masks.

(Effects of the Invention) As described above, according to the present invention, it is possible to minimize the adhesion of the residue of the intermediate layer SOG film to the remaining film thickness of the lower resist film. It becomes possible to form a resist pattern.

[Brief explanation of drawings]

Fig. 1 is a process cross-sectional view showing an embodiment of the present invention, Fig. 2 is a view showing the relationship between the remaining film thickness of the lower resist film and the intermediate layer SOG film residue density, and Fig. 3 is a cross-sectional view of the main part of the tE device. 4 is a diagram showing the magnetic field dependence of self-bias, and FIG. 5 is a process sectional view showing problems in the conventional example. In the figure, 1 is the substrate, 2 is the A1 film, 5 6 3 is the lower resist film, 3' is the lower resist film, 4 is the intermediate SOC film, 4' is the intermediate SOC film pattern, and 5 is the upper resist film. , 5' is the upper resist film pattern, 6 is the intermediate layer SOC film residue, 7 is the lower resist film residue, 11 is the magnet, 12 is the high frequency electrode, 13 is the ground electrode, 14 is the substrate, 15 is the high frequency power supply, h is the lower layer The remaining thickness of the resist film is: 103- JP-A-3-66119 (6) WaO 0 00 Magnetic field dependence of self-buy γnu 11'l: between Fig. 4 and process cross-section shown between the interposition point of conventional booklet and Fig. 5 Fig. 105-

Claims (2)

[Claims] (1) A lower organic resin film (3), an intermediate metal resin film (4), and an upper organic resin film (5) are sequentially formed on the substrate (1) on which the thin film (2) has been formed, and then by photolithography. An upper layer organic resin film pattern (5') is formed, then dry etching is performed using the upper layer organic resin film pattern (5') as a mask to form an intermediate layer metal resin film pattern (4'), and then the upper layer organic resin film pattern (4') is formed. Dry etching is performed using the film pattern (5') and the intermediate metal resin film pattern (4') as a mask to form a lower organic resin film pattern (3').
and etching the thin film (2) using the lower organic resin film pattern (3') as a mask, the method comprises etching the thin film (2) using the lower organic resin film pattern (5') and the intermediate organic resin film pattern (5'). In the process of dry etching the lower layer organic resin film (3) using the layer metal resin film pattern (4') as a mask, the upper layer organic resin film pattern (5') is etched away and the middle layer metal resin film pattern (4') is etched away. ') The thickness of the upper organic resin film (5) is set so that the remaining thickness of the lower organic resin film (3) does not exceed 1 μm when the surface of the semiconductor device is exposed. Production method. (2) A lower organic resin film (3), an intermediate metal resin film (4), and an upper organic resin film (5) are sequentially formed on the substrate (1) on which the thin film (2) has been formed, and then by photolithography. An upper layer organic resin film pattern (5') is formed, and then dry etching is performed using the upper layer organic resin film pattern (5') as a mask to form an intermediate layer metal resin film pattern (4'). A lower organic resin film pattern (3') is formed by reactive ion etching using the film pattern (5') and the intermediate metal resin film pattern (4') as a mask and applying a magnetic field, or the upper organic resin film pattern (3') is By performing dry etching using the resin film pattern (5') and the intermediate layer metal resin film pattern (4') as a mask, the upper layer organic resin film pattern (5') is etched away and the intermediate layer metal resin film pattern (4') is etched away. After the surface of 4′) is exposed, reactive ion etching is performed while applying a magnetic field to form a lower organic resin film pattern (3′),
A method for manufacturing a semiconductor device, comprising the step of etching the thin film (2) using the lower organic resin film pattern (3') as a mask.