JPH0498823A - Spin coating - Google Patents

Abstract

PURPOSE:To restrain the evaporation of the solvent even if it is a coating agent containing a solvent at low boiling point i.e., an easy to be dried up solvent for avoiding the uneven painting step thereby enabling the spin coating of the coating agent to be performed in excellent reproducibility by a method wherein the spin-coating step is performed in a solvent gas atmosphere. CONSTITUTION:A substrate 1 to be coated is carried onto the spinning base 11 in a spin-coating chamber 4 from a leading-in chamber 5 to be fixed on the base 11. A solvent gas is led into the spin-coating chamber 4 once exhausted at the pressure of e.g. about 40-100Pa(Pascal) e.g. in the SOG coating-step from a leading-in port 15 to produce the solvent gas atmosphere in the chamber 4. In such a state wherein the evaporation of the solvent can be restrained, a coating agent is dripped on said substrate 1 to be spin-coated by spinning the spinning base 11 at e.g. 6000r.p.m for 5-60 sec. Later, the spinning step is continued for about 1-2min to make even the undulated surface shape and the enevenness on the whole surface.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is applicable to photoresists used in the manufacturing process of semiconductor devices, for example, and coated glass materials so-called SOC (spin-on coating).
It relates to the spin coating method applied to various spin coatings such as on glass), polyimide resin, etc.

[Summary of the invention]

The present invention provides a spin coating method in which a coating material containing a solvent is spin-coated onto a substrate. To avoid uneven coating due to evaporation of a solvent in the coating, and to form a homogeneous coating film.

[Conventional technology]

SOG (for example, photoresist) applies to manufacturing technology of various devices including semiconductor device manufacturing technology.

A spin coating method for polyimide resin and the like is often used.

For example, photoresist materials are applied for the purpose of etching resists such as wet etching and dry etching, plating resists, etc. in patterning various materials such as metals, semiconductors, and insulators, and SOG and polyimide resins are used for patterning materials such as semiconductor integrated circuits. These photoresists,
OG1 polyimide resin and the like are widely used as a surface flattening layer on an uneven underlying surface.

These photoresists, SOC, polyimide resins, etc.
The coating material contains a solvent such as an alcohol or a cellosolve solvent, thereby adjusting the fluidity, viscosity, etc., so that even and uniform coating can be achieved by spin coating.

However, with this coating material, there is a problem that the composition changes due to evaporation of the solvent during spin coating, making it impossible to maintain the desired fluidity, spreadability, viscosity, etc. When coating a substrate to be coated such as a semiconductor wafer, this change in formulation not only causes uneven coating, but also causes problems in reproducibility due to the large dependence on changes in coating conditions such as ambient temperature. Specifically, if a large amount of a low boiling point solvent, for example methanol (boiling point ~64.7° C.) is included, the coating material dries quickly, resulting in a large coating thickness at the center.

Further, in the case of spin coating, there is a problem in that the surface of the coating material is undulated due to the performance of the spin coating lid, that is, the motor of the spin coater, and the formed coating surface has a wavy shape. As a method of suppressing the occurrence of such a wavefront shape, for example, when using an organic SOG material, 3.000
~ 4.0OOr, p, m, Te It is also possible to rotate for about 15 seconds, then stop the rotation and leave it to use its fluidity to smooth the surface, that is, flatten it, and then perform heat treatment. However, this method has a problem in that it is difficult to apply to coating materials that use low boiling point or volatile solvents.

[Problem to be solved by the invention]

An object of the present invention is to solve problems such as uneven coating and decreased reproducibility due to variations in the composition due to evaporation of the solvent in the coating material in the above-mentioned spin coating method of the coating material.

[Means to solve the problem]

The present invention is a spin-coating method for spin-coating a coating material containing a solvent onto a substrate, in which the coating material is spin-coated in a solvent gas atmosphere.

[Effect]

As described above, in the present invention, the evaporation of the solvent is suppressed by performing spin coating of the coating material in a solvent gas atmosphere. Therefore, it is possible to stably maintain the initial formulation from the beginning of spin coating to the end without being sensitively affected by surrounding conditions such as temperature, and to achieve uniform spin coating, for example. The surface flattening can be achieved reliably and with good reproducibility.

〔Example〕

An embodiment of the spin coating method according to the invention will be described along with a bag wall on which the method is implemented. FIG. 1 shows a configuration diagram of an arrangement for carrying out the method of the present invention, and in this example, a substrate to be coated (1
) For example, a cassette containing a large number of semiconductor wafers (2
) is placed, an introduction chamber (5) from which substrates to be coated (1) are sequentially taken out in a single wafer manner and introduced into a rotary coating chamber (4) to be described later, and a substrate to be coated. (1) A spin-coating chamber (5) for spin-coating a target coating material thereon, and a delivery chamber for sending out the coated substrate (1) coated with the coating material in this spin-coating chamber (5) to another part, for example. (6
), followed by a heating chamber [7], and further followed by an unloader chamber (8) in which the substrates to be coated (1) are housed and placed in the required cassettes (2), which are opened and closed sequentially through an opening/closing door (9). Can be configured with a closed lid.

The rotary coating chamber (4) is equipped with heating means, such as a heater (10), for applying the required heating, and the coating chamber (4) is equipped with, for example, '!'! As shown in Fig. J2, the substrate to be coated (1) is placed on a rotary table (11) that rotates the substrate (1) within its plane, for example, around the center of the substrate (1).
is placed above the rotating table (11), and a dripping nozzle (1) for dropping the target coating material onto approximately the center of the substrate to be coated (1) placed on the rotating table (11). 12
) is opened, and a coating material introduction pipe (13) whose outer end is connected to a coating material supply source (not shown) is arranged. Also,
This rotary coating chamber (4) is provided with an exhaust port (14). This exhaust port (14) is connected to exhaust means such as a vacuum pump. Furthermore, this rotary coating chamber (4) also has a solvent gas inlet (1) for introducing a solvent gas used in the coating material.
5> is provided.

In this configuration, first, a cassette (2) containing a substrate to be coated (1), for example, a semiconductor wafer, is placed in a low goo chamber (3).
). On the other hand, the introduction chamber (5) is provided with an exhaust port (16) connected to a vacuum pump, for example, and the delivery chamber (6) is provided with a gas introduction port (17) through which the required gas is introduced.
) is provided.

Then, the loader (3) is placed in the exhaust introduction chamber (5).
A substrate to be coated (1), for example, a semiconductor wafer, is taken out and introduced one by one from the cassette (2). Then, the substrate to be coated (1) is brought from the introduction chamber (5) onto the rotary table (11) of the rotary coating chamber (4), and is fixed on the rotary table (11). The rotary coating chamber (4) is first evacuated and the pressure is set at 40 to 100 Pa, for example, when wiping the SOG coating.
(Pascal) and then inject the solvent gas into its inlet (
15) into the rotary coating chamber (4), and the rotary coating chamber (
4) Create a solvent gas atmosphere inside. In this way, under conditions where the evaporation of the solvent can be suppressed, the coating agent is dropped from the nozzle (12) onto the substrate to be coated (1), and then the rotating table (11)
For example, spin coating is performed by rotating the coating at 6000 r, p, rn for 5 to 60 seconds. Thereafter, the coating is left for about 1 to 2 minutes to smooth out the wavy shape on the surface and the unevenness of the entire surface of the substrate, and after making the surface uniform, the inside of the spin coating chamber (4) is evacuated again. Then, the coating is heated by a heating means (10) at a relatively low temperature of 200° C. or lower to evaporate the solvent in the coating film.

At this time, drying starts from the low-boiling point solvent of the coating film, but since this drying occurs after the coating has already been applied to the entire surface, it evaporates, so the effect of film density fluctuations, that is, uneven coating, on the coating film due to the evaporation of the solvent is small. Avoided. After that, the sending room (6
], the substrate to be coated (1) is led out, and here the introduction port (
For example, N2 inert gas is introduced from 17) to bring the pressure to atmospheric pressure, and then the mixture is brought to the heating chamber (7). The inside of the heating chamber (7) is set to an atmosphere of, for example, N or an inert gas, and has, for example, a plurality of hot plates A, B, and C, with a first hot plate A
For example, heating is performed at 100° C. for 10 seconds in the second hot plate), 290° C. for 10 seconds in the second hot plate B, and 400° C. for 60 seconds in the third hot plate C. Thereafter, the substrates to be coated (1) are sequentially brought to the unloader chamber (8) and housed in a cassette (2), which is then carried out to another section.

Note that the apparatus for carrying out the above-mentioned spin coating is not limited to the above-mentioned example, and can be modified in various ways. For example, the heating means for the heating chamber (7) is not limited to a hot plate, but may also be an electric furnace or a tunnel. The heating chamber (7) can be formed by a furnace, etc., and the heating chamber (7) can also be used as the delivery chamber (6), or if it is, the introduction chamber (5) can be omitted. It can be harvested.

Moreover, the transfer and handling of each of the substrates (1) described above can be performed automatically by a robot.

〔Effect of the invention〕

As mentioned above, in the present invention, the spin coating of the coating material is performed in a solvent gas atmosphere, so even if the coating material contains a low boiling point, that is, a solvent that is easy to dry, the evaporation of the solvent is suppressed. Therefore, the coating material can be spin coated without uneven coating and with good reproducibility.

For example, as shown in FIG. 3, a concavo-convex pattern of electrodes, wiring, etc.
18), the method of the present invention can form a smooth flat surface as shown by the solid line, even though the surface state of the chain lIa in the figure is uneven, as shown in the figure.

Moreover, by performing spin coating on the entire surface and spraying off the solvent over the entire surface, a coating film having excellent and stable film quality can be formed.

In addition, since the evaporation of the low boiling point solvent in the coating material during coating is suppressed, the above-mentioned uneven thickness due to composition changes is avoided, and the coating material is involuntarily dried, so that the coating material is not dried before the coating film is baked. This prevents the inconvenience of inhibiting the effect of keeping the stationary state and eliminating the wavefront, and furthermore, that the coating material in the coating film turns into powder before baking, which causes dust generation. It is possible to form a uniform and stable coating film with good reproducibility, such as avoiding changes in the characteristics of semiconductor elements or contamination of manufacturing equipment in the subsequent manufacturing process of semiconductor devices, etc.

[Brief explanation of drawings]

FIG. 1 is a linear configuration diagram of an example of an apparatus for carrying out the method of the present invention, FIG. 2 is a linear sectional view of the rotary coating chamber thereof, and FIG. 3 is a sectional view showing the coating state. (1) is the substrate to be coated, (4) is the rotating coating chamber, (11) i
2 rotary tables, (14) an exhaust port, (15) a solvent power inlet, and (12) a supply pipe having a solvent dripping nozzle. Agent Hidemori Matsukuma

Claims (1)

[Scope of Claims] A spin coating method for spin coating a coating material containing a solvent onto a substrate, characterized in that the spin coating of the coating material is performed in a gas atmosphere of the solvent.