JPH03154668A - Method and apparatus for forming organic membrane - Google Patents

Abstract

PURPOSE:To form an org. membrane used as a photoresist or a color film having a uniform surface by accumulating fine droplets containing org. matter on a substrate and volatilizing the solvent contained in the fine droplets to form a build-up membrance. CONSTITUTION:Fine particles 20 of org. matter and the solvent of the fine particles 20 are bonded in a container 30 to form fine droplets 20c containing the org. matter. The fine droplets 20c are accumulated on a substrate 1 and the solvent contained in the fine droplets 20c is volatilized to form a build-up membrane. As a result, an org. membrane having no coating irregularity or thickness irregularity and used as a photoresist or a color film having a uniform surface can be formed.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for forming an organic thin film used as a photoresist or a color filter on a substrate when manufacturing semiconductor devices, liquid crystal displays, etc. The present invention relates to a thin film forming apparatus.

C. Prior Art/Problems to be Solved by the Invention] In the manufacturing process of semiconductor devices, liquid crystal displays, etc., many steps including multiple photolithography steps are performed on a substrate made of silicon, gallium arsenide, glass, etc. Over time, transistors, wiring, and other elements were built in.

In the process of forming these elements, various uneven shapes are created on the substrate, and in the photolithography process during this process, these unevenness cause problems as detailed below. Sometimes.

For example, in the photolithography process in the conventional semiconductor device manufacturing process, in many cases, an organic thin film such as photoresist is formed on a substrate using a spin coating method, and a desired pattern is applied to this using ultraviolet light or the like. A resist pattern is obtained by transferring and developing. FIG. 9 is a schematic cross-sectional view schematically showing a conventional organic thin film forming apparatus using the spin coating method. It is a chuck that is held on its upper surface by a method, and has a vacuum introduction path inside and a suction port formed at the top (not shown).

The chuck (2) is connected to the motor (4) via the spindle (3).
), and by rotating the motor (4), the substrate (1) is rotated. A nozzle (5) is arranged above the substrate (1), and the nozzle (5) is connected to a storage container for a coating solution such as photoresist (not shown). Further, a resist cup (6) is arranged to surround the substrate (1) and the chuck (2), and an opening (6a) is formed in the upper part of the resist cup (6), and a drain (6b) is provided in the bottom part. ing.

In the spin coating method, first, as shown in FIG. 10a, a coating is applied onto the substrate (1) held on the chuck (2).
Coating solution (7) such as photoresist from nozzle (5)
is dripped in the required amount. Subsequently, as shown in FIG. 10b, by rotating the motor (4) (not shown),
The substrate (
1) is rotated in a horizontal plane, and the centrifugal force generated at this time spreads the coating solution (7) on the substrate (1) from the center to the periphery. At this time, the excess coating solution (7a) is removed from the substrate (1).
) is blown away, collected into the resist cup (6), and discharged from the drain (6b). By further continuing the rotation, the solvent in the coating solution (7) on the substrate (1) evaporates, and finally a thin film (7b) of photoresist etc.
) hatched (Figure 10c).

In addition, in the manufacturing process of color image sensors, liquid crystal color displays, etc., in the process of forming on-chip type or on-wafer type color filters on substrates such as silicon or glass, when forming a thin film of filter material on the substrate. The above-mentioned spin coating method is used for this purpose.

Since the conventional organic thin film forming method is configured as described above, the coating solution (7) on the substrate (1) is dispersed from the center of the substrate (1) by the centrifugal force generated by the rotation of the substrate (1). In the process of flowing to the periphery, there is a problem in that radial film thickness unevenness is likely to occur due to unevenness on the surface of the substrate (1), as shown in FIG.

FIG. 11 is a plan view schematically showing the result of spin coating a coating solution on a substrate (1) on which a relatively large uneven shape is formed in the manufacturing process of a semiconductor device, and in the figure, 00) is 1 A plurality of chips 01) corresponding to each semiconductor device are scribe lines for isolation between these chips QO1. In many cases, the scribe line 01) is about 1 to 5 times lower in height than the chip 001 portion, and has a step with a width of about 50 to 100 degrees. When a liquid or paste coating solution is spin-coated onto a substrate (1) having such unevenness using a conventional spin-type thin film forming apparatus as shown in FIG.
As shown in the figure, since the flow of the coating solution is disturbed by the uneven parts on the substrate (1), radial coating unevenness, that is, film thickness unevenness (+21) occurs.
2) may appear even if the height of the step is relatively small, on the order of several tenths of a micron to several microns.

The above-mentioned uneven coating is caused by photoresist film,
This poses a problem of reducing the dimensional controllability of patterns formed by etching or the like using this, and sometimes causes disconnections or short circuits in pattern wiring. In addition, in on-chip color filters for color image sensors and on-wafer color filters for liquid crystal color displays, such coating unevenness causes the filter film to become uneven, resulting in variations in spectral sensitivity characteristics and non-uniformity. The problem arises.

Furthermore, the spin coating method has a problem in that the surface of the photoresist film is not flat due to the unevenness of the surface of the substrate (1), as shown in FIGS. 12a-c, and has a wavy shape.

12a-c are cross-sectional views schematically showing the surface shape of a photoresist film (8) obtained by applying a photoresist solution onto a substrate (1) having three different types of uneven shapes on the surface. It is.

The surface of the substrate (1) shown in FIG. ) is not flat but has a wavy shape. Further, the shape of the undulations (8a) is asymmetrical due to the influence of the flow of the photoresist liquid, and is not as symmetrical as compared to the uneven shape of the underlying pattern. Therefore, when aligning the exposure pattern by detecting the uneven pattern (13) with a laser beam or the like, the asymmetry of the shape of the photoresist film (8) causes a deviation in the detection signal, which impairs the alignment accuracy. The problem arises that the amount of energy decreases.

Also, as shown in Figures 12b and 12c, the substrate (1
) Even if the pattern is as simple as one convex part 041 or concave part 041 on the surface of the undulation, due to this asymmetry, the center of the convex part or four parts of the undulation (14a, 15a) will be misaligned, and the convex part There is a problem in that there is a difference in the thickness of the photoresist film (8) on the left and right sides of the portion 04) and the recessed portion 4, which reduces dimensional controllability.

Similar problems occur with on-chip color films for color image sensors.

The present invention has been made to solve the above-mentioned disadvantages and problems, and provides a method for forming an organic thin film used as a photoresist, color filter, etc., which has a uniform surface without uneven coating or film thickness. The present invention also aims to provide an apparatus for forming the organic thin film.

[Means to solve the problem]

The present invention involves combining fine organic particles and a solvent for the fine particles in a container to form fine droplets containing the organic substance, depositing the fine droplets on a substrate, and volatilizing the solvent contained in the fine droplets. A method for forming an organic thin film is characterized in that a chamber surrounding a space in which the organic particles and the solvent of the particles are combined is provided with an inlet for the organic particles and a solvent gas and/or A mist inlet is provided,
The present invention further relates to an organic thin film forming apparatus including a chuck for holding a substrate within the chamber.

〔Example〕

FIG. 1 is an explanatory diagram showing how microdroplets containing organic matter are formed in the method for forming an organic thin film of the present invention. In the figure, (1) is a substrate, and (20a) is a fine organic particle that has begun to dissolve in a solvent, (20b) is a fine organic particle that has further dissolved in a solvent and is in a semi-dissolved state, (20c) is a fine particle of an organic substance that is dissolved in a solvent. The diagonally shaded area of the microdroplet containing the organic substance in a uniform solution state indicates a space filled with a solvent atmosphere.

In the method of the present invention, fine particles of an organic substance to be formed into a film are combined with a solvent for dissolving them in a container to form particles 1 (20a to 20c) containing organic substances.

The organic substance is not particularly limited as long as it can be dissolved in a solvent, but specific examples include organic substances that can be used as color filter materials such as photoresist materials, transparent resins, gelatin, and casein. The particle size of the organic particles is preferably about 0.1 to 1O-, and more preferably ultrafine to about 0.05 to 0.5O. When the particle size is less than 0.1 am, the individual fine particles combine with each other to form aggregates, and the particle size tends to become substantially large. There is a tendency that it becomes difficult to maintain the uniformity of a thin film having a thickness below.

The solvent can be appropriately selected depending on the organic substance to be formed into a film, the film forming conditions, etc., and specific examples include organic solvents such as ethyl cellosolve acetate and xylene, and in the case of water-soluble organic substances. Water, etc. can be given.

The bonding between the organic particles and the solvent creates, for example, a solvent atmosphere space in which a part of the chamber-like container (the shaded area in Figure 1) is filled with the solvent in the form of gas or mist. Microparticles of organic matter dispersed and suspended in a carrier gas such as dry air or nitrogen gas are introduced into the space, and the microparticle heads are caused to fall downward under the action of an external force such as gravity and pass through the solvent atmosphere space n. The method is preferred.

The solvent atmosphere space is filled with organic matter particles.
The height of the rope must be large enough to allow enough time for the solvent to adsorb the solvent as it passes through, and - for boat fishing, a height of about 30 cm to 1 m is desirable. Also, the width in the horizontal direction is the substrate (1
) is preferably about 1.5 to 5 times the width or diameter. In addition, the solvent concentration ranges from almost saturation (100%) to 809%.
Up to about 6 is appropriate.

In the process of passing this particle head through the solvent atmosphere space,
By adsorbing solvent gas or adhering solvent mist to the fine particles (■), the fine particles (■) change from particles (20a) that have begun to dissolve in the solvent, to particles (20b) that are semi-dissolved, and then completely dissolve. This results in fine droplets (20c).

Next, the microdrops (20c) are deposited on the substrate (1), and the solvent contained in the microdrops (20c) evaporates to form the desired organic thin film.

To deposit the droplet (20c) on the substrate (1), the substrate (
1) may be placed below the solvent atmosphere space (2) in the direction of gravity. At this time, in order to further improve the uniformity of the film thickness, the substrate (
1) may be rotated.

When the fine droplets are deposited on the substrate, it is necessary that the fine droplets come into contact with each other and that bonding begins from this contact area. In addition, in order for the combined microdroplets (20d) that are combined and integrated to have a uniform composition, it is preferable that the organic matter is completely dissolved in the microdroplets (20c), but some of the organic matter has begun to dissolve in the solvent. Particles in a state (20a) and particles in a semi-dissolved state (20a)
0a).

The size and concentration of the fine droplets can be controlled by the particle size of the fine particles, the solvent concentration in the solvent atmosphere space, the height of the solvent atmosphere space and the chamber, etc., but the size of the fine droplets depends on the uniformity of the thin film to be formed. 1/10 of the desired film thickness to improve surface smoothness and surface flatness! It is desirable to control the particle size to about /100.

The fine 1 (20c) deposited on the substrate (1) is the second a-
As shown in Figure c, the surface of the substrate (1) is wetted, and the adjacent droplets (20c) come into contact with and combine with each other, forming bonded droplets (20c).
20d) is formed. Then, the microdroplet (20c) and the combined microdroplet (20d) combine and integrate over time,
The surface tension flattens the surface and forms a thin film.

There is no particular limitation on the method of volatilizing the solvent. For example, as shown in FIG. 2c, after forming a thin film,
The solvent can be volatilized by baking at about 00°C.

In the above example, the state shown in FIGS. 2a-c, that is, the particles 1 (20c) are deposited on the substrate (1), and these are combined,
The process of forming a thin film mainly depends on the bonding force due to the surface energy of these fine droplets.
By heating to about 00°C, the bonding force of these microdroplets may be increased and the change to the thin film (2V state) may be promoted. In addition, the solvent concentration in the vicinity of 2'D increases as the solvent evaporates, forming a thin film. The rate of volatilization from C21+ decreases, but the fourth
As shown, this region may be evacuated to increase the rate of volatilization. Furthermore, methods such as the beta treatment, substrate heating, and exhaust may be used in combination as appropriate.

By the method of the present invention as described above, it is possible to produce a uniform organic thin film with a thickness of about 0.5 to 50 mm, which is useful as a photoresist, a color filter, etc., without any unevenness in film thickness.

Next, examples of the organic thin film forming apparatus of the present invention will be described in Sections 5 to 5.
This will be explained using Figure 8.

FIG. 5 is a schematic cross-sectional view showing one embodiment of an organic thin film forming apparatus, in which (1) is a substrate, (a is a chuck that holds the substrate (1) by a method such as vacuum suction, and ■ is a substrate (1). ) is a cylindrical chamber located above the
A particulate inlet (31) of the chewing device is provided at the upper part thereof through a conical portion. Further, a solvent inlet (32) is provided on the side of the chamber (2). The chamber volume is typically 2 for deposition on 6-inch silicon wafers.
The weight is usually about 0 to 100 g, and the height is usually about 0.5 to 2 rA.

Further, for the purpose of improving the uniformity of the thickness of the thin film, a device may be provided for rotating the substrate (1) during deposition of the microdroplets.

In the apparatus configured as described above, as described above, particulate particles of organic matter such as photoresist are sent through the particulate inlet (31) on a carrier gas such as dry air. A solvent gas or solvent mist that dissolves the fine particles (2) is fed into the chamber (2) from a solvent inlet (32), forming a solvent atmosphere space. Note that the hatched area in the chamber is a representation of a high concentration area in the solvent atmosphere space (the same applies to FIGS. 6 to 8). The fine particles in the upper part of the chamber are so small that they float, but they gradually fall down due to the action of gravity.
It combines with the solvent in the solvent atmosphere space and forms fine droplets (20c
), which further falls and is deposited on the lower substrate (1). These spaces are shielded from the outside world by chamber (2) to prevent disturbances caused by external air currents.

After depositing a predetermined amount of microdroplets (20c) on the substrate (1), the introduction of the microparticles (2) and the solvent is stopped, and the thin film on the substrate (1) is prebaked to form the desired thin film. .

Since the device basically deposits material in the vertical direction, radial film thickness unevenness and coating unevenness due to steps on the substrate do not occur, and the thin film does not become asymmetrical before and after the uneven pattern.

Next, another embodiment of the organic RH forming apparatus of the present invention will be described with reference to FIG.

In the figure, the lower part of the chamber (■) is in close contact with the chuck ('2J) via a seal (30), which seals the inside of the chamber (ω). Also, there is an exhaust port (33) on the lower side wall of the chamber (■). In this device, there are three introduction ports (31) for organic particles, from which the particles (3) are fed.
32) are provided at two locations on the left and right sides, thereby expanding the solvent atmosphere space in the vertical direction.

The chuck (2) has a stepped shape, and by a vertical movement mechanism (not shown), when it is in the upper position as shown in Fig. 6, it contacts the seal (34) and closes the opening at the bottom of the chamber ω. If it is in the lower position, the board (1)
It becomes possible to replace the In addition, by providing multiple fine particle introduction ports (31) like this device, large diameter,
It becomes possible to form a film even on a large-area substrate (1).

In the device configured as above, the micro 1 (20c) is connected to the substrate (
1) During deposition, the exhaust port (33) is closed with a valve or the like (not shown), and after a predetermined amount of fine droplets (20c) have been deposited, the introduction of the fine particles ■ and the solvent is stopped by operating the valve, etc. . Next, the valve of the exhaust port (33) is opened to exhaust the atmosphere near the thin film on the substrate (1). This promotes solvent volatilization from the thin film and forms an organic thin film. In addition, by opening the exhaust port (33) and adjusting the exhaust volume even during the deposition of the fine droplets (20c), the solvent concentration on the substrate (1), the solvent concentration in the solvent atmosphere space, etc. It is also possible to adjust the concentration distribution within the droplets (20c), and by these adjustments, it is possible to change the solvent content, viscosity, surface tension, etc. in the microdroplets (20c) deposited on the substrate (1).

In the apparatus shown in FIG. 6, the substrate (1
) The viscosity of the deposited film depends on the size and depth of the uneven shape on the top.
Physical properties such as surface tension can be changed, and conditions for flattening the uneven shape of the base can be optimized. In addition, as mentioned above, this device does not, in principle, cause defects such as radial coating unevenness or asymmetry in the surface shape of the thin film at the front and back positions of uneven shapes as shown in FIG. 11. .

Next, another embodiment of the organic thin film forming apparatus of the present invention will be described with reference to FIG.

The basic structure is the same as the device explained using FIG. 6, but in this device, a heater (35) is embedded in the chuck (a. ).The chuck (2) is in close contact with the chamber through a seal (34) at its side wall, maintaining airtightness within the chamber ω and preventing turbulence due to the influence of external airflow. An inlet (31) for fine particles (3) and a solvent inlet (32) are provided at the top of the chamber (2), and the area directly below these serves as a solvent atmosphere space, in which fine droplets (20c) is generated.

In the apparatus shown in FIG. 7, the heater (35) is connected to the chuck (2).
The substrate (1) is optionally heated through 1 to promote the transformation of microdroplets <20c) and bound microdroplets (20d) into thin films as described above. In addition, after the thin film is formed,
Together with the effect of exhaust from the exhaust port (33), this promotes the volatilization of the solvent from within the thin film. Furthermore, it is also possible to perform a flattening process on the thin film within the chamber by heating with a heater (35).

In addition, in the apparatus shown in FIG. 7, the heater for heating is shown as an example embedded in the chuck (a), but it may be installed on the outer periphery of the chamber (2), or it may be placed inside.Furthermore,
An optical glass window may be provided on the side wall of the chamber and may be heated from the outside by a radiation light source such as an infrared lamp, or these may be used in combination.

Next, an embodiment of an apparatus provided with means for making the dispersion state of the particles (1) more uniformly distributed through the particle introduction port (31) into the chamber mark will be described with reference to FIG.

The basic structure is the same as that of the apparatus described above with reference to FIG. 6, but a dispersion gas inlet (38) is provided in the upper part of the conical chamber (2).

In addition, a mesh (37) and a honeycomb-shaped rectifier tube (38) are vertically installed below the chamber inside the chamber.4 The formation mechanism of the organic thin film on the substrate (1) is the same as described above. Since they are similar, their explanation will be omitted, and the newly added items will be explained.

Depending on their physical properties, the fine particles transported by the carrier gas such as dry air through the fine particle inlet (31) tend to aggregate and may not be sufficiently dispersed. It is also effective to use some kind of dispersion means to uniformly disperse the particles within the chamber. The apparatus shown in Fig. 8 has a structure in which a dispersion gas such as dry air is applied to the fine particles flowing in through the inlet (31) through the dispersion gas inlet (3B), and the particles are uniformly dispersed within the chamber. It is said that

By adjusting the direction of the dispersing gas inlet (36), the state of the air flow generated within the chamber may be changed, for example, into a weak swirling flow.

The mesh (37) and the rectifying cylinder (38) prevent the influence of the air flow at the upper part of the chamber ink pad from reaching the lower solvent atmosphere space and the space above the substrate (1), and the mesh (3γ)
The weakened airflow becomes a weak airflow that flows vertically by the rectifying cylinder with holes facing vertically.

In the apparatus shown in FIG. 8 as well, when the required amount of microdroplets (20c) are deposited on the substrate (1), the supply of microparticles and solvent is stopped through the inlet (31), and the dispersion gas is introduced. The blowing of dry air from the mouth (36) is stopped.

As shown in FIG. 8, by using a dispersion gas and its inlet (36) as a means for dispersing particulate particles, and a mesh (37) and a rectifying cylinder (37) as a rectifying means,
It becomes possible to make the organic thin film formed on the substrate (1) more uniform.

In the apparatus shown in FIG. 8, an example is shown in which a gas such as dry air is used as a dispersing means, but the present invention is not limited to this, and mechanical means such as a rotating blade or a vibrator may also be used.

The organic thin film forming apparatus of the present invention is not limited to the apparatus shown in FIG. The position, number, shape, and position, number, shape, etc. of the exhaust ports (33) are not limited to those illustrated.

〔Effect of the invention〕

As described above, according to the method and apparatus for forming an organic thin film of the present invention, a thin film is formed by depositing fine droplets containing an organic substance on a substrate. It is possible to prevent the cross-sectional shape of the membrane from becoming asymmetrical. Therefore, in the case of a photoresist film, for example, there is an effect that line width controllability, positioning accuracy during pattern exposure, etc. can be improved.

In addition, in the case of a color filter film, the uniformity of its spectral characteristics can also be improved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing how fine droplets containing organic matter are formed; FIGS. 2a-c are explanatory diagrams of the process of forming an organic thin film in the present invention; FIG. 3 is an explanatory diagram showing heat treatment; The figure is an explanatory diagram showing exhaust treatment, Figures 5 to 8 are schematic sectional views of the organic thin film forming apparatus of the present invention, Figure 9 is a schematic sectional view of a conventional organic thin film forming apparatus, and Figures 10a to 10c are Explanatory diagram of the process of forming an organic thin film using a conventional organic thin film forming apparatus, No. 11
The figure is a plan view schematically showing a coating film obtained by a conventional method, and FIGS. 12a-12c are cross-sectional views schematically showing the surface shape of a coating film obtained by a conventional method. (Symbols in drawings) (1): Substrate ■: Organic particles (20c): Microdroplets containing organic substances (2D; thin film n: solvent atmosphere space ■: Chamber (31): Organic particle inlet <32) : Solvent inlet (33) : Exhaust port (34) : Seal (35) : Heater (3B) : Gas inlet for dispersion (37) : Mesh (38) : Rectifier tube 2
a Dimensions 2b Diagrams 2c Dimensions 1 Well 3 Figure 4 Figure 5 Figure 31: Particle inlet 32: Solvent inlet Figure 7 65: Heater Figure 6 Figure 1 36: Exhaust port size 8 Figure 66: For dispersion Gas inlet 37: Mesh 38: Rectifier tube 9 Figure 5 Fang 10a Figure 10b Figure 10C Figure 12a Book (self-produced)

Claims (2)

[Claims] (1) Organic fine particles and the solvent of the fine particles are combined in a container to form fine droplets containing the organic substance, the fine droplets are deposited on a substrate, and the solvent contained in the fine droplets is evaporated. A method for forming an organic thin film, the method comprising forming a deposited film. (2) An inlet for the organic particles and an inlet for the solvent gas and/or mist are provided in a chamber surrounding the space where the organic particles and the solvent for the particles are combined, and the substrate is further placed in the chamber. An organic thin film forming device equipped with a holding chuck.