JPH03215931A - Formation of photoresist - Google Patents

Abstract

PURPOSE:To avoid the thickening of a photoresist film at stepped parts thereby enabling a film thickness to be unified even if a semiconductor or thin film head is covered with the stepped parts by a method wherein a substrate is coated with photoresist solution using the electrostatic spray coating process to form a photoresist film. CONSTITUTION:The photoresist solution contained in a solution tank 1a is pressure-fed by a pump 2a into a classification chamber 4 while being air- sprayed from a spray nozzle 3a. The classified particles passing through a particle pipe 7 are discharged from the end of a coating nozzle 8 onto a substrate 12. At this time, a film can be formed of the particles receiving charges from a corona discharge needle 11 along the stepped parts on the substrate 12. Successively, the substrate 12 is coated with the photoresist solution contained in another solution tank 1b and pressure-fed by another pump 2b. Through these procedures, even if the substrate 12 is covered with the stepped parts, the photoresist film in even thickness can be formed since the carged resist particles are applied along the stepped parts on the substrate 12.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of application in industry]
- The present invention relates to a method for forming a photoresist on a resist 1, and particularly relates to a method for forming a photoresist suitable for forming a resist 1 with a uniform thickness even when a step exists on a substrate.

[Conventional technology]

A spin coating method is mainly used as a photoresist forming method in the conventional semiconductor and thin film head element forming process. With this method, uniform resist 1 to films can be formed with high accuracy on a flat substrate surface. However, if there is a step on the surface of the strand, the thickness of the resist will be non-uniform at the step, making it impossible to pattern the device with high precision. In particular, in the semiconductor manufacturing process, in order to shift the line width to submicron levels, it is necessary to design elements with a step height of 1 μm or less. In addition, in the case of a thin film 1 mm, the element step difference is 10 μm or more, so in the spin coating method, the film from HO 1 to resist 1 becomes hot at the step part, and the patterning accuracy between HO 1 and resist 1 during track width processing is affected. This has led to a decline in yield, making it difficult to improve yield.

As related to the present invention, JP-A-62-61.67
There is an invention disclosed in Publication No. 2. The invention disclosed in the above-mentioned publication aims at uniform coating in an electrostatic coating method, and is intended to uniformly coat an organic photoreceptor on a cylindrical support. However, there is no mention of unevenness on the surface of the cylindrical support. In addition, until now, using electrostatic coating method,
No technology has been reported for forming a resist film on a semiconductor or film head.

[Problems to be Solved by the Invention] 3 The problems of the prior art using the spin coating method will be explained using the cross-sectional view of the thin film device shown in FIG. In FIG. 3, 21 is the substrate, 22 is the lower magnetic material, 23 is the gap film, 24 is the coil, and 25 is the green material ++
a, 26 indicates a -1 two-part magnetic material, and 27 indicates a film of baho 1 to resist 1. As shown in FIG. 3, in the conventional spin coating method, the step length Q3 of the magnetic material 26 is 10μ.
m or more than 1-], the formed photoresist film 27
The values of v, -Q1, and Qz (films) greatly differed, and it was difficult to form films 1 to 27 having uniform thicknesses.

In addition, the conventional technique of electrostatic coating described above involves forming a film from the hole 1 to the resist 1 on the semiconductor or film head, and uniformly forming the film thickness when there are irregularities on the semiconductor or film head 1.・
However, no consideration has been given to the formation of a photoresist film having a uniform thickness on an uneven surface.

The present invention prevents the film thickness of the photoresist 1 to become thicker at the step part even when there is a step difference in a semiconductor or a photoresist film head, and forms a photoresist film with a uniform thickness. It is an object of the present invention to provide a method for forming a hole resist 1, which is capable of forming a resist 1.

[Means to solve the problem]

The method for forming a photoresist film of the present invention includes applying a photoresist solution onto a substrate using an electrostatic spray coating method,
It is characterized by forming a film.

Further, according to the present invention, in the above-mentioned electrostatic spray coating method, the Hole 1-Resist 1 solution is such that the Hole 1-Resist 1-made of a resin containing a photosensitizer is contained in a proportion of 20 parts by weight or less to the solution. It is characterized by being configured.

Further, according to the present invention, when forming a photoresist film by the electrostatic spray method, the first photoresist 1 solution and the second photoresist solution having mutually different concentrations and composition ratios are successively applied. You can do it like this. In this case, the first solution is formed to have a lower boiling point than the second solution.

Furthermore, according to the present invention, the electrostatic spray coating may be performed after surface treatment to make the surface of the substrate uniform in electrical conductivity.

[Effect]

According to the present invention, even if there is a step on the substrate-1, the charged resist 1 fine particles are coated along the step on the substrate, so that the photoresist 1 with a uniform thickness can be applied.
A single film can be formed.

At that time, Hole-Resist 1~ made of resin containing photosensitizer
By making the ratio of 20 parts by weight or less to the solution, the size of the particles applied to the substrate becomes smaller and a good film can be formed. I can do it.

In addition, by sequentially applying the first Hole Regis 1 ~ solution and the second Hole Regis 1 ~ solution having different concentrations and composition ratios, for example, the static state of the first Hole Regis 1 ~ solution can be Relatively large photoresist particles are applied to the substrate-1- by electrostatic coating, and then relatively small photoresist particles 1-1 are applied by electrostatic coating of the second photoresist solution, thereby increasing the film thickness. It becomes possible to form a uniform and good resist film.

Furthermore, by forming the first resist solution to have a boiling point lower than that of the second resist solution, film sag at the stepped portion can be prevented by forming the first resist solution. A uniform photoresist film whose surface is leveled by the second photoresist solution can be formed.

Furthermore, by carrying out the electrostatic spray coating described above after performing a surface treatment to make the electrical conductivity of the surface of the substrate uniform, it is possible to easily form the films 1 to 1 with uniform film thickness at the stepped portions. becomes possible.

〔Example〕

The present invention will be described in more detail below with reference to embodiments shown in the accompanying drawings.

FIG. 1 is an explanatory view showing an example of an electrostatic coating apparatus for carrying out the resist forming method of the present invention. In Figure 1, solution tanks ia and 1-b accommodate solutions 1 to 1. The solution tank 18 contains a photosensitive group-containing novolak resin in parts by weight as solutions HO1 to REGIS1 to #, and 30 parts by weight of ethyl cellosolve acetate-1 to (hereinafter referred to as ECA) and butyl acetate as solvents. It contains a solution containing 70 parts by weight. The solution tank 1b also contains the novolak resin as a photoresist solution. ]Includes parts by weight,
A solution containing 70 parts by weight of ECA and 30 parts by weight of butyl acetate is contained as a solvent.

] - In the embodiment shown in the figure, the solution contained in the solution tank ia is supplied to the tank 4 by the bomb 2a.
0kg/. ffl pressure, and spray nozzle 3
The air is sprayed into the classification chamber 4 by a. At the same time, nitrogen gas is supplied from the supply/exhaust nozzle 6 as a carrier gas. It is supplied into the classification chamber 4 at a rate of OOff/min. At this time, the diameter is 1 μm to 1
The Photores I solution, which has been atomized to 00 μm, and nitrogen gas hit the classification brake 1-5, producing an airflow in the direction of -A in the figure. However, among the fine particles in Regis 1 to solution, large ones have a large inertial force, so the diameter is 50 μm to 100 μm.
Particles with particle diameters larger than 12 are removed by adhering to classification blades 1 to 5. Here, the particle size controller 1 can be rolled by changing the flow rate and flow rate of the carrier gas. - It passes through the particulate carrier pipe 7 and is ejected from the tip of the coating nozzle 8 towards the substrate 12. This emission is 300
It took place in seconds. At that time, fine particles are discharged from the corona discharge needle]
By receiving an electric charge from the substrate 12, a film can be formed along the second step of the substrate 12''.

Subsequently, as a second step, the photoresist solution contained in the solution tongue 1b is heated for 40 ky by the bomb 2b.
It is fed under a pressure of /a# and applied to the substrate 12 in the same manner as in the first step. The second step of release was carried out over a period of 200 seconds.

Hole 1 ~ Regis 1 ~ in the solution tank 1a used in the first step
Since the solution contains a large amount of butyl acetate, which has a low boiling point, a large amount of the solvent in the fine particles evaporates and is applied in a highly viscous state. Therefore, sagging of the film at the step portion on the substrate 12 is prevented, and the film can be formed along the step.

However, since surface leveling is poor in the first step alone, in the second step, a Hole Regis I solution containing a large amount of ECA with a high boiling point is used to form fine particles with a high solvent content and low viscosity. Apply. As a result, a uniform film with a leveled surface can be formed.

At this time, a voltage of 10 to 20 kV generated by the high voltage power supply 9 is applied to the fourth corona discharge via the high voltage cable 10, and the substrate stage 13 is placed in a state where a ground or positive voltage is applied.

Further, the substrate stage 13 has the functions of parallel movement and rotation and revolution, and the uniformity of the film formed on the substrate 12 is improved by parallel movement and rotation and revolution.

Here, if the above-described steps 1 and 2 are repeatedly performed on a plurality of substrates J2,
In order to reduce the film thickness variation between the two layers, it is important to control the atmosphere inside the coating chamber 14. Therefore, it is necessary to install the gas concentration sensor 16 and control the amount of exhaust from the wandering hole 15 so that the concentration change of the solvent gas during the resist coating process for each substrate 12 is constant within the range of 15 to 25%. It is.

Furthermore, in order to reduce variations in film thickness between the base holes 12, it is desirable to keep the temperature and humidity of the room in which the entire apparatus is installed constant.

In order to obtain a uniform resist I film along the stepped portion of the substrate J2, it is desirable that the surface of the substrate 12 has a uniform quality (for example, electrostatic property, etc.). Therefore, a good surface can be obtained by, for example, sputtering gold onto the surface of the substrate 12 by about 100 people.

Furthermore, in order to reduce the thickness of the resist film and apply it uniformly, it is effective to place the substrate in hexamethyldisilazane vapor to improve the wettability of the surface.

Generally, the size of the photoresist particles coated on the substrate can be increased by adjusting the ratio to 20 parts by weight or less to the photoresist solution made of a resin containing a photosensitive agent. It is possible to form a small and good resist film.

FIG. 2 is a sectional view of an element in which a resist film is provided on a thin film head according to the embodiment shown in FIG.

In FIG. 2, the same parts as those in the conventional example shown in FIG. 3 are given the same reference numerals. As is clear from FIG. 2, in the step portion of the two-part magnetic body 26, the film thickness of the film 27 does not become thicker, and the thickness of the film 11 is uniform. 27 was formed. Specifically, for example, when the step difference in a part of the magnetic material is 10 μm, the film thickness of the hole resist 1 film 27 at the step portion is 6 μm, and the film thickness of the hole resist 1 film 27 at the top of the step portion is 6 μm. It was 5 μm.

-I In the embodiment described above, in the first step and the second step, the solution from the heregis 1 in the classification chamber 4 was jetted out by air spray, and nitrogen gas was supplied from the supply/exhaust nozzle 6, but the present invention does not do this. When ejecting the solution from the resist 1 into the classification chamber 4, the solution is injected into the classification chamber 4 in advance at a nitrogen gas pressure of 3 kg/ci and a solution pressure of 1 kg/d to the resist 1, for example. They may be mixed and air sprayed. At that time, if necessary, exhaust the excess nitrogen gas from the supply/exhaust nozzle 6,
The flow rate and flow rate of the resist 1 to solution particles from the coating nozzle 8 may be rolled to the controller 1.

As is clear from the following explanation, in order to obtain a film thickness of 5 μm at the top of the step with a 10 μm thin-film head element step, the conventional spin coating requires a 10 μm resist at the bottom of the step. However, in this embodiment, this can be reduced to 5 μm. As a result, the track width dimensional accuracy of the thin film head finally obtained was 5.0 ± 1.0 μm.
．． Improved to 6 μm.

In the following explanation, the fine particles of the resist solution are charged and spray coated, but the present invention is not limited to this, and spray coating may be performed without imparting a charge. You can also do it.

〔Effect of the invention〕

As is clear from the following explanation, according to the present invention, even if there is a step in the semiconductor or thin film head, the thickness of the film between the hole 1 and the resist 1 can be prevented from increasing at the step portion. It becomes possible to form a film of uniform thickness.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing an example of a photoresist electrostatic coating apparatus for carrying out the method of forming a film according to the present invention;
The figure is a sectional view of a thin film head coated with Photoresist 1 film using the photoresist l-electrostatic coating device shown in Figure 1.
The figure is a sectional view of a thin film head coated with a single film of heat resist 1 according to the prior art. la, lb...Regis 1 to solution tank, 2a, 2b
...Pump, 3a, 3b...Spray nozzle, 4.
...Classification chamber, 5...Classification plate, 6...
Supply/exhaust nozzle, 7... Particulate carrier vibe, 8...
Coating nozzle, 9... High voltage power supply, ]0... High voltage cable, 11... Corona discharge needle, 12... Substrate, 13
... Substrate stage, 14... Coating chamber, 15.
...Exhaust hole, 16...Gas concentration sensor, 21...Substrate, 22...Lower magnetic film, 23...Gap llu
, 24 Coil, 25 Insulating film, 26 Two-part magnetic material, 27 Photoresist l-film.

Claims (5)

[Claims] 1. A method for forming a photoresist film on a substrate, the method comprising: applying a photoresist solution onto the substrate using an electrostatic spray coating method to form a photoresist film. 2. 2. The method of forming a photoresist according to claim 1, wherein the photoresist solution used in the electrostatic spray coating method contains photoresist made of a resin containing a photosensitizer at a ratio of 20 parts by weight or less to the solution. . 3. 2. The method of forming a photoresist according to claim 1, wherein in the electrostatic spray method, a first photoresist solution and a second photoresist solution having mutually different concentrations and composition ratios are successively applied. 4. 4. The method of claim 3, wherein the first photoresist solution has a lower boiling point than the second photoresist solution. 5. 2. The method of forming a photoresist according to claim 1, wherein the electrostatic spray coating is performed after surface treatment to make the electrical conductivity of the surface of the substrate uniform.