JPS6235264B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method and apparatus for applying hexamethyldisilazane to a substrate or various thin films formed on a substrate. In the manufacturing process of semiconductor integrated circuit elements, superconducting logic circuit elements, Josephson junction elements, etc.
A photoresist or an electron beam resist is applied to the surface of a substrate (wafer) such as SiO ₂ or Si ₃ N ₄ and exposed and etched (lithography). One of the important technical issues in such lithography is how to uniformly apply a resist to a substrate with good adhesion. Conventionally, in order to improve the adhesion between the substrate and the resist, hexamethyldisilazane [(CH ₃ ) ₃ SiNHSi(CH ₃ ) ₃ : hereinafter referred to as "HMDS"] was applied to the substrate surface before resist application. (See Special Publication No. 47-26043). Common methods for applying HMDS include a spin coating method and a gas diffusion method. This method uses a resist spinner to apply the HMDS liquid to the substrate, but the HMDS liquid scatters inside the spinner, making it inefficient. Furthermore, HMDS attached to the inner wall of the spinner
becomes vapor and reacts with water vapor in the air to form hexamethyldisiloxane [(CH ₃ ) ₃ SiOSi(CH ₃ ) ₃ :hereinafter,
"HMDX"] and ammonia (NH ₃ ),
This HMDX adheres to the surface of the HMDS film coated on the substrate in the form of many spots, and as a result, the adhesion with the resist is impaired in the spots, resulting in the tearing of the resist film in spots and uniformity. Difficult to apply resist. In addition, the odor of ammonia is so strong that it cannot be removed and affects work. This method involves exposing the substrate to HMDS vapor using a closed container such as a desiccator.
As the steam reacts with the water vapor in the air inside the sealed container and the water vapor inevitably generated from the inner wall of the container, many spot-like breaks in the resist film caused by HMDX are scattered and caused problems, similar to the former case. Come. On the other hand, a coating method that avoids the influence of HMDC due to the reaction between HMDS vapor and atmospheric water vapor has recently been proposed as the vacuum bake/vaper prime system. This method involves placing the substrate in a vacuum container and adding a dehydration bake at high temperature before and after exposing the substrate to HMDS vapor. That is, place the substrate in a vacuum container and
At a high temperature of ~200°C, vacuum evacuation → nitrogen gas replacement → vacuum evacuation → HMDS vapor introduction → vacuum evacuation → nitrogen gas replacement, so compared to the methods of and.
Due to the reaction between HMDS vapor and atmospheric water vapor
The impact of HMDX is small. However, as soon as the evacuation is stopped, water vapor is generated from the inner wall of the vacuum container, and the reaction between this water vapor and HMDS vapor causes
The effects of HMDX cannot be avoided, and the contamination of the board due to the backflow of oil and paper from the vacuum pump (rotary pump) cannot be ignored, or the seal of the vacuum pump due to the evacuation of ammonia cannot be ignored. It is not an effective method as corrosion can cause malfunctions. Furthermore, an important problem with this method is that dehydration baking is performed at high temperatures. That is, in manufacturing superconducting logic circuit elements including Josephson junction elements, it is necessary to further form multiple layers of superconducting thin film patterns on the pattern of superconducting thin films formed on the substrate. In this case, HMDS is applied on top of the superconducting thin film without oxidizing it.
However, applying HMDS after dehydration baking at high temperatures will oxidize the superconducting thin film. Furthermore, since a vacuum pump and a chamber that can withstand the pressure of the vacuum are required, the equipment for carrying out this method has the disadvantage of being expensive. Although attempts have been made to use a vapor flow method in which HMDS vapor is simply transported to the substrate surface using a carrier gas such as nitrogen, no consideration has been given to eliminating water vapor from the substrate surface before and after applying HMDS. Similarly, many spots of resist film breakage due to HMDX cannot be avoided. As described above, all of the conventionally known HMDS coating methods have various drawbacks, so as mentioned above, in the manufacturing field, especially in the LSI manufacturing field which requires patterns of about 2 μm, it is necessary to develop an effective HMDS coating method. The current situation is that there is a demand for this. The present invention has been made in view of the above, and provides a method for simply and easily applying HMDS to a substrate or various thin films formed on a substrate, and a simple and inexpensive HMDS coating device that can be used directly to implement this method. The purpose is to The purpose of this is to pre-treat the substrate surface by flowing nitrogen gas, and then to
In the HMDS coating method, steam is flowed over the surface of the substrate to apply HMDS to the surface, and then nitrogen gas is flowed to post-treat the coated surface, during which time the substrate is constantly isolated from the water vapor by the flow of nitrogen gas. It is achieved by doing so. This object further comprises a nitrogen gas source, an enclosed space containing the substrate, a container containing HMDS in liquid phase, and two-position flow switching means, the flow switching means having one switching position in which the nitrogen gas is removed. A source of nitrogen gas is connected to said enclosure via flow path switching means, at the same time the flow path from said container is closed, and in the other switching position a source of nitrogen gas is connected to said container, and said container is connected to said container. This is achieved by an HMDS applicator connected to the enclosed space of the HMDS. Hereinafter, the present invention will be explained in detail with reference to the accompanying drawings. FIGS. 1 and 2 are an example of an apparatus for carrying out the present invention. 1 is a nitrogen gas source, 2 is an enclosed space that accommodates the substrate 3, 4 is a container that accommodates the HMDS liquid 5, and 6 is a two-position flow path switching means (for example,
WHITEY valve, SS-43YF2), 7 is a flow meter for nitrogen gas, and 8 is a meter for HMDS steam conveyed by nitrogen gas. First, by setting the two-position flow path switching means 6 to one switching position (the state shown in FIG. The flow board 3 is pretreated. Next, when the two-position flow path switching means is set to the other switching position (the state shown in FIG. 2) and nitrogen gas is caused to flow into the HMDS liquid in the container 4 through the pipeline 10, the nitrogen gas becomes a carrier gas and flows through the pipe. HMDS vapor flows into the surrounding space 2 through lines 11 and 9 and HMDS is applied to the surface of the substrate. Finally, the two-position flow path switching means 6 is returned to one switching position (the state shown in FIG.
The surface of the HMDS film coated on the substrate is post-treated. In this way, in the present invention, the steps from initial substrate pretreatment to HMDS application and post-treatment are performed in a continuous flow of nitrogen gas through a pipeline, so that the water vapor in the air and the HMDS vapor can be mixed. Not only the reaction but also the reaction between the water vapor released from the inner wall of the container and the HMDS vapor is almost avoided, and the above-mentioned reaction is avoided.
Failures caused by HMDX are excluded. Further, since the present invention performs each of the above steps at room temperature without interrupting the flow of nitrogen gas, oxidation of the substrate or various thin films formed on the substrate can be prevented. Furthermore, in the present invention, as shown in FIGS. 1 and 2, the flow of nitrogen gas and HMDS vapor passes through a narrow gap between the substrate 8 and the flat plate 12 facing the same, and then passes through an exhaust gas provided at the center of the parallel plates. Since they flow quickly to the port 13, their usage can be reduced. FIG. 3 shows an example in which the HMDS coating apparatus of the present invention is applied to a spinner for coating resist. The surrounding space that accommodates the substrate 3 is the spinner 1
4 and a flat plate 12 which is disposed with a narrow gap (approximately 1 mm) opposite the surface of the substrate disposed thereon and has an exhaust port 13 in the center. The flat plate 12 is fixed to a holder 16 and can be moved up and down via a flexible cover 17. Now, connect the pipeline 9 of the HMDS coating device shown in FIG. 1 or 2 to the gas supply port 19 provided on the side wall of the lid 18 of the spinner 14, apply HMDS to the substrate by the method described above, and then remove the holder. 16 is lifted upward, and the resist is supplied from the resist supply port 20 to the HMDS coated surface of the substrate, and the resist is coated with a spinner. As a result, high-purity nitrogen gas carries away water vapor in the air or water vapor released from the inner wall of the container, and the flowing nitrogen gas constantly blocks water vapor released from the surface of the substrate and the inner wall of the container. The entire process from HMDS coating to post-processing to resist coating can be performed consistently without any trace of the high-purity nitrogen gas flowing over the substrate surface. In this way, the present invention shown in FIGS.
The HMDS coating equipment has a simple configuration, and when the purity of flowing nitrogen gas is 10 ppm, it is equivalent to performing all processes in a vacuum of approximately 7.6 mTorr.
In addition, it is extremely inexpensive because it does not require a vacuum container or a vacuum pump that can withstand vacuum pressure. In addition,
In the apparatus of the present invention, unlike the above-described method, the gas pressure in the pipelines 9 and 10' for guiding the gas is 1 atm or higher, so that even if there is a gap, the purity of the nitrogen gas flowing over the substrate surface does not deteriorate. The flat plate 12 is made of a light-transmitting material such as quartz, and the light is transmitted through it.
By irradiating the substrate with ultraviolet light before applying HMDS, the substrate surface is activated, so HMDS on the substrate is
Easy to apply. After coating the substrate with HMDS using the apparatus shown in FIGS. 1 and 2, the surrounding space 2 is transferred to a spinner as it is, and the substrate is taken out from the surrounding space while adjusting the flow meter 7 to flow a large amount of nitrogen gas. It can be placed on a rotating table of a spinner to perform spinner coating of resist. Example Using the HMDS coating equipment shown in Figures 1 and 2, purity
The method of the present invention was carried out by flowing 10 ppm nitrogen gas into each step at the flow rates shown in the table below.

[Table] As a result, the attachment of the resist (AZ1350) to the substrate was perfect, there were no spotty resist tears caused by HMDX, and a 2 μm AZ1350 pattern was obtained with good reproducibility.

[Brief explanation of the drawing]

Figures 1 and 2 are front views showing an example of an apparatus for carrying out the HMDS coating method of the present invention, and Figure 3 is a cross-sectional view of the HMDS coating apparatus of the present invention applied to a spinner for resist coating. The front view shown. Codes in the diagram: 1...Nitrogen gas source, 2...Enclosed space,
3... Substrate, 4... Container, 5... HMDS liquid, 6... Two-position flow path switching means, 9, 10, 11... Pipeline, 12... Flat plate, 13... Exhaust port, 14... Spinner, 15... Rotating table.

Claims (1)

[Claims] 1. Pretreat the surface of the substrate by flowing nitrogen gas, and then apply hexamethyldisilazane to the surface by flowing the vapor of hexamethyldisilazane carried by the nitrogen gas onto the surface of the substrate. A method for applying hexamethyldisilazane, which is characterized in that the applied surface is subsequently treated by flowing nitrogen gas, and during this period the substrate is constantly isolated from water vapor by the flow of nitrogen gas. 2. A nitrogen gas source, an enclosed space containing the substrate, a container containing liquid phase hexamethyldisilazane,
and a two-position flow path switching means, in one switching position of the flow path switching means said nitrogen gas source is connected to said enclosure via said flow path switching means, and at the same time said flow path from said container is connected to said enclosure space through said flow path switching means. Apparatus for application of hexamethyldisilazane, characterized in that it is closed and in the other switched position said nitrogen gas source is connected to said container, and said container is connected to said enclosure. 3. The enclosed space for accommodating the substrate is constituted by a rotating table of a spinner and a flat plate having an exhaust port in the center, which is installed with a gap between the rotating table of the spinner and the surface of the substrate placed above the rotary table. A coating device for hexamethyldisilazane according to Scope 2. 4. The hexamethyldisilazane coating device according to claim 3, wherein the flat plate is a light-transmitting material.