JPH05217959A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a semiconductor device and a manufacturing method thereof in which dry-etching may be applied under same etching conditions, simultaneously and optimally to a film under patterns having different opening sizes. CONSTITUTION:Impurities are doped in advance into the places 4 of a film 2 to be etched where an etching speed becomes relatively small due to a micro- loading effect, thereby eliminating a difference in the etching speed due to a difference in the opening size.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device. More specifically, the present invention is a method of manufacturing a semiconductor device capable of eliminating a difference in etching rate of a film to be etched due to a microloading effect when performing dry etching using a mask pattern in which patterns having different opening sizes are mixed. Regarding

[0002]

2. Description of the Related Art With the recent demand for high integration of semiconductor devices, there is an increasing demand for fine pattern processing technology.

Therefore, a dry etching technique suitable for processing a fine pattern has been provided. That said, as the opening size of the etching mask pattern formed on the film to be etched becomes smaller, the etchant becomes less likely to enter the mask opening, so that the etchant hardly reaches the film to be etched, and as a result, The etching rate of the film to be etched depends on the opening size of the etching mask pattern, that is, the smaller the opening size, the slower it becomes (microloading effect).

Therefore, when patterns having different opening sizes are present in the same etching mask pattern, the etching rate of the film to be etched below the etching mask pattern having a large opening size and the etching speed at the lower part of the etching mask pattern having a small opening size. A difference may occur in the etching rate of the etching film. Due to the micro-loading effect, the difference in the etching rate of the film under the mask pattern with such large and small opening dimensions becomes particularly problematic in addition to the opening dimension of the mask pattern and the film to be etched and the underlying layer. Although it cannot be said unconditionally because the selection ratio of the film to the etching is also related, it is the case where the opening size of the smaller mask pattern is about 1.0 μm or less.

In the dry etching of the conventional semiconductor device manufacturing method, in order to solve such a problem, the difference in etching rate of the film to be etched based on the difference in the opening size of the etching mask pattern is eliminated by selecting the etching conditions and improving the etching apparatus. I was trying.

[0006]

However, no matter how well the etching conditions are selected, it is essential to eliminate the difference in the etching rate of the film to be etched due to the microloading effect due to the difference in the opening size of the etching mask pattern. Impossible. Therefore, when the dry etching of the film to be etched under the etching mask pattern having the large opening size is completed, the dry etching of the film under the etching mask pattern having the smaller opening size is not yet completed.

Therefore, when patterns having large and small opening sizes are mixed in the same etching mask pattern, after the etching of the film under the mask pattern having the large opening size is completed, the mask pattern under the mask pattern having the smaller opening size is further removed. It has been necessary to perform overetching until the etching of the film to be etched is completed. With this,
If the over-etching time is not optimal, the etching of the film below the etching mask pattern with the smaller opening size may not be completely achieved, and depending on the etching conditions of the film to be etched, the layer below the film to be etched may not be completely etched. The selection ratio of the film becomes small, so that overetching may damage the exposed lower layer film in the region of the large opening size where the etching has been completed.

In view of the above points, the present invention simultaneously dry-etches a film to be etched under a pattern having different opening dimensions under the same etching conditions even if the opening dimensions of the same etching mask pattern are different. Another object of the present invention is to provide a semiconductor device manufacturing method that can be optimally performed.

[0009]

According to a method of manufacturing a semiconductor device of the present invention, an etching mask pattern in which patterns having different opening sizes are mixed is formed on a film to be etched, and the film to be etched under the mask pattern is dried. In a method of manufacturing a semiconductor device including a step of removing by etching, impurities are preliminarily injected into a film to be etched at a portion where an etching rate is relatively small due to a microloading effect at the time of dry etching, and the film at the portion is removed. It is characterized in that the etching rate of the etching film is made equal to the etching rate of the film to be etched in other portions.

According to the method of the present invention, the dry etching is performed by using an etching mask pattern in which two or more opening sizes are mixed, which has a pattern having an opening size of about 1.0 μm or less in which the decrease of the etching rate due to the microloading effect is particularly remarkable. It is particularly effective when etching is performed.

The impurities to be injected into the film to be etched are generally arbitrarily selected according to the material of the film. The injection amount and the injection depth can also be set arbitrarily. For example, when it is not preferable to implant impurities into the lower layer film of the film to be etched, it is possible to implant high-concentration impurities into only the upper portion of the film to be etched. In addition, in the case where the portions to which the impurities are to be injected are adjacent to each other and the film between them remaining after the etching may include the impurities (for example, the film to be etched is a conductor film) In addition, it is possible to collectively implant the impurities into a wider region including a plurality of locations where the impurities should be implanted.

As described above, the type of impurities and the amount of implantation thereof are
The implantation depth and the implantation method can be arbitrarily determined as long as the dry etching rate is the same at the impurity-implanted portion and the non-implanted portion.

The film to be etched may be any film. That is, the method of the present invention can be advantageously applied to any film used in the manufacture of semiconductor devices.

[0014]

Operation: Impurities are implanted in advance into the film to be etched at a portion having a small opening size of the etching mask pattern, and the etching rate of the film to be etched at that portion is set to a value other than that in which no impurity is implanted and the opening size is larger. By making the etching rate of the etching target film at a location equal to that of the etching target film, it is possible to simultaneously and optimally dry-etch the etching target films under all the opening patterns under the same etching conditions.

[0015]

EXAMPLE An example of the method of the present invention will be described below.
In this example, a large opening of 3 μm and a small opening of 0.8 μm were formed by dry etching in the polysilicon film to be etched on the silicon substrate according to the procedure described below.

As shown in FIG. 1A, a silicon substrate 1
A resist 3 for impurity implantation is applied onto the upper polysilicon film 2 (thickness 0.3 μm) and patterned to correspond to a portion corresponding to an opening of 0.8 μm to be formed in the polysilicon film 2. The opening 4 was provided. Then, phosphorus was ion-implanted into the polysilicon film 2 in the opening 4 portion using the resist 3 as a mask. At this time, the acceleration voltage was 40 kV and the doping amount was 3 × 10 ¹⁵ cm ^-2 .

Next, the resist 3 is peeled off, the resist 5 for etching is applied to the entire surface of the exposed polysilicon film 2 and patterned, and a large opening size (3 μm) and a small opening size (0 μm) for dry etching are applied. A mask pattern of 0.8 μm) was formed (FIG. 1 (b)).

Dry etching is performed using the etching mask pattern thus formed, the resist is peeled off, and 3 μm is formed on the polysilicon film 2 as shown in FIG. 1 (c).
m openings and 0.8 μm openings were formed. For both opening sizes, the polysilicon film was completely removed by etching, and no overetching of the underlying silicon substrate 1 was observed. As described above, by implanting phosphorus as an impurity in a portion having a small opening size, it is possible to optimally etch a portion having a large opening dimension and a portion having a small opening dimension in the same etching time.

Various other aspects can be considered as the embodiment of the present invention. For example, although the resist pattern is used as a mask at the time of implanting phosphorus in the above-described embodiment, any mask that is effective as a mask for implanting impurities can be used. Also, for the formation of the impurity implantation mask pattern, a technique such as direct drawing with an electron beam can be used in addition to patterning using a mask.

Further, even if the film left after the dry etching (polysilicon film 2 in FIG. 1C) contains the implanted impurities, there is no problem, and the opening size is small as shown in FIG. 1A. Rather than forming an impurity implantation mask pattern for each etching pattern, a large opening pattern is collectively formed in a region adjacent to a pattern having a small opening size (a region indicated by A in FIG. 1A). Injection may be performed.

[0021]

As described above, according to the present invention,
Even if the opening dimensions of the same etching mask pattern are different, the films to be etched under the patterns having different opening dimensions can be simultaneously and optimally dry-etched under the same etching conditions. Therefore, incomplete removal of the film to be etched under the pattern with a small opening size,
Alternatively, it is possible to avoid damage to the base under the pattern having a large opening size due to overetching, and it is possible to greatly contribute to the improvement of the performance and reliability of the semiconductor device.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a procedure for carrying out a method of the present invention, in which (a) is a diagram illustrating formation of a mask pattern for impurity implantation and impurity implantation, and (b) is a mask for dry etching. FIG. 6 is a diagram illustrating formation of a pattern, and (c) is a diagram illustrating a state after dry etching.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Silicon substrate 2 ... Polysilicon etching film 3 ... Impurity injection resist 4 ... Impurity injection opening 5 ... Dry etching resist

Claims (2)

[Claims] 1. A method of manufacturing a semiconductor device, comprising the steps of forming an etching mask pattern in which patterns having different opening sizes are mixed on an etching target film and removing the etching target film under the mask pattern by dry etching. Impurities are preliminarily injected into the film to be etched at a location where the etching rate is relatively small due to the microloading effect during dry etching, and the etching rate of the film to be etched at that location is adjusted to that of the film to be etched at other locations. A method of manufacturing a semiconductor device, wherein the etching rate is set to be equal to the etching rate. 2. The method according to claim 1, wherein the opening dimension of the etching mask pattern at the portion where the impurities are implanted is 1.0 μm or less.