JP3163147B2 - Resist evaluation apparatus, resist coating apparatus and resist coating method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for applying a resist formed on a photomask substrate or a semiconductor substrate used for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art LSI (Large Scale Integrated Circuit)
High integration of semiconductor devices such as it) is remarkably progressing four times in three years. Therefore, it is extremely important to suppress the occurrence of defects such as wiring patterns formed on a semiconductor substrate to obtain a high yield. In the process of manufacturing a semiconductor device, in forming a wiring pattern and the like, a resist film is obtained by dropping a resist solution onto a substrate such as a photomask substrate or a semiconductor substrate which is spinning at an appropriate rotation speed. Then, a mask having a desired wiring pattern or the like is exposed and transferred to the resist film, and is subjected to an appropriate developing process to obtain a resist image. The resist image obtained in this manner is applied to an underlayer formed on the substrate, for example, Si
It is used as a mask when etching metal such as O ₂ or Al. Therefore, if there is a defect between or in the patterns of the formed resist image, the defect is etched and transferred to the base, causing a short circuit or open circuit of the wiring, thereby lowering the yield of the LSI. That is, L
In order to achieve high yield in the manufacture of SI, it is important to reduce defects in a resist image (resist pattern) formed on a substrate. One of the factors that cause defects between resist patterns is particles in the resist film. The particles are generated by dust generation in a resist solution supplied from a resist manufacturer or in a resist supply system as shown in FIG. Particles themselves are chemically or physically segregated in the composition of the resist solution, and are generated from contact materials such as manufacturing vessels, pumps, valves, etc. during the production of the resist film or in the resist coating system in the resist supply system described above. It is roughly divided into rigid dust. The above-described resist or resist film is for exposure, and here,
Photoresist. The present invention can be applied not only to light exposure but also to a resist for beam exposure such as X-rays and electron beams.

In a conventional resist supply system, first, a resist solution 1 is stored in a resist tank, as shown in FIG. The resist solution 1 therein is dropped onto a semiconductor substrate (wafer) or the like which is spinning from a discharge nozzle 7 through a pipe 2, and a resist film is formed on the substrate. A pump 3, a filter 4, a suck-back valve 5, and a stop valve 6 are formed in a pipe 2 connecting the tank and the discharge nozzle. And these valves 5,
The pump 6 and the pump 3 are connected via a control unit, and adjust the supply of the resist solution. The filter 4 is used for manufacturing a resist film or a manufacturing container in a resist coating apparatus.
Removes rigid dust generated from contact materials such as pumps and valves. In this manner, the rigid dust or particles can be removed by the filter 4, but the one formed by segregating the resist composition is subjected to Poise stress deformation of the membrane filter by the pressure received by a pump or the like. It easily passes through the filter.

[0004]

[0007] A stress-deformable particle formed by segregation of the resist composition is gel-like and has a certain resist flow rate even if the pore size of the membrane is as small as possible. In order to remove it, it must be extruded with a large pressure, and easily passes through the filter due to deformation due to increasing stress. The gel-like particles are generated over time depending on the storage and use conditions of the resist, and cause defects such as wiring patterns formed by the resist film formed on the substrate. Determining the quality of the resist film has been performed so far. For example, Japanese Patent Application Laid-Open No. 1-178958 discloses a method for detecting foreign matter inside and outside a resist film. This method is intended to modify the resist film in order to facilitate the detection of foreign matter, and furthermore, scattered light is used for detection light. Detecting gelled dust is very difficult. The present invention has been made in view of such circumstances, and a resist evaluation apparatus for reducing defects in a wiring pattern formed on a substrate, a resist coating apparatus and a resist coating method using the evaluation apparatus. It is intended to provide.

[0005]

The present invention is characterized in that before applying a resist solution to a sample, the number of particles in the resist solution is measured and the characteristics of the resist solution are evaluated based on the number. That is, the resist evaluation apparatus of the present invention is a unit for supplying a resist solution, a transparent monitor substrate to which the resist solution is applied, and a resist film formed from the resist solution on the monitor substrate is irradiated, and A light source for generating light transmitted through the monitor substrate and a light detector for detecting light transmitted through the monitor substrate are provided. The means for supplying the resist liquid has a means for allowing the resist liquid to freely fall on the monitor substrate. Further, a laser beam can be used as the light source. When the monitor substrate falls freely from the means for supplying the resist liquid, the monitor substrate can be inclined horizontally. The resist coating apparatus according to the present invention includes a means for supplying a resist liquid, a transparent monitor substrate on which the resist liquid is coated, a resist film formed on the monitor substrate formed from the resist liquid, and the monitor substrate A light source that generates light that transmits light, a resist evaluation device that has a light detector that detects light that transmits through the monitor substrate, a sample support table that supports a sample to which the resist liquid is applied, and the resist liquid. A device for moving the supply means on the monitor substrate or the sample. The sample supporter receives an excess resist solution generated from the means for supplying the resist solution, and is further placed in a coater (coating) cup for discharging the excess resist solution. The monitor substrate of the resist evaluation device is arranged in the cup; Further, the resist coating method of the present invention includes a step of forming a resist film by applying a resist liquid on a surface of a transparent monitor substrate; a step of irradiating the resist film with light; and a step of irradiating the resist film with light. Detecting the number of particles of the resist film from the state of scattering of the detected light, and detecting the number of particles of the resist film from the back side of the monitor substrate.
A step of applying the same resist liquid as the resist liquid applied to the monitor substrate to the sample to form a resist film only when the number of ticles is equal to or less than an allowable value.

[0006]

Since the resist solution can be evaluated before the resist solution is applied to the substrate, a resist solution having good characteristics can always be used for the resist supply system.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a resist coating apparatus according to a first embodiment of the present invention. A sample, for example, a silicon wafer 13 is held by a spin chuck 14 which is rotated by a spin motor 15. Way
The c 13 is placed horizontally on the spin chuck. A resist liquid is dropped from the discharge nozzle 7 onto the rotating wafer 13. Since the wafer 13 is rotating, the resist solution is uniformly applied to form a resist film having a uniform thickness. Of the resist liquid dropped from the discharge nozzle 7, an extra resist liquid that does not contribute to the formation of the resist film is
Is discharged. For this purpose, a discharge hole (drain) 16 is formed at the bottom of the coater cup 17 which accommodates the wafer 13, the spin chuck 14 and the spin motor 15. The coater cup 17 further has a sub chamber.
The evaluation device is arranged there. On the upper surface of the sub-chamber, there is a discharge port 8 into which a resist liquid dropped from a discharge nozzle 7 is put, and a monitor substrate 9 made of a transparent glass plate is arranged below the discharge port 8. The dropped resist solution is uniformly applied to the inclined surface of the monitor substrate 9, and the excess resist solution naturally falls to the bottom of the sub chamber,
It is discharged from the drain 16 in the main chamber. As described above, since the evaluation device is installed together with the coating device in the coater 17 where the coating is performed, the movement of the discharge nozzle 7 can be efficiently performed, and the entire device can be downsized.

In this embodiment, the monitor substrate 9 is tilted and the resist solution is applied uniformly using gravity.
May be spin coated.
A light source 10 is arranged to face the inclined surface of the monitor substrate 9. Since the light source is opposed to the monitor substrate 9 which is inclined, the light source is provided obliquely with respect to the sub chamber. As long as a light source is used in the evaluation device, it is advantageous to tilt the monitor substrate without using spin coating. A semiconductor laser is used as the light source, that is, the light irradiating unit 10, but it is not necessary to limit to this, and a wavelength of 500 to 8
Any light source that generates light of about 00 nm may be used. The photoresist of this embodiment is a commonly used material at present. If the wavelength of the light from the light source is within the above range, light can be sufficiently transmitted through the materials commonly used at present. Absorption starts with the material. However, in the future, there is a high possibility that a material that can be used even when the light wavelength is about 300 nm or less will be developed. The discharge nozzle 7 is connected to a conventional resist supply system as shown in FIG.
Further, since a resist solution must be supplied not only to a sample such as a wafer but also to an evaluation device, a moving mechanism is provided. The evaluation device is further provided with a scattered light detector (light receiving element) 11 including a light receiving element on the back surface of the monitor substrate 9 to detect transmitted scattered light transmitted from the light source through the monitor substrate. Excess resist solution dropped on the monitor substrate is cleaned and removed by a cleaning nozzle 12 provided near the monitor substrate. Now, after moving the discharge nozzle 7 to the discharge port 8 at the entrance of the sub-chamber, the resist solution is, for example,
A resist film is formed by being dropped on a transparent monitor substrate 9 made of glass. Next, the wavelength λ emitted from the laser diode from the light irradiation section 10 is 780
The light is transmitted through the monitor substrate, scattered, and detected by the light receiving element 11. The detected transmitted scattered light is analyzed by photoelectric conversion, and as a result, the particle diameter and the number of dust particles in the resist film can be known. The monitor substrate 9 is made of a resist film, for example, quinonedia.
A solvent such as ethyl cellosolve acetate or 3-methoxymethylpyrionate, which dissolves a novolak resin-based resist using a zide as a photosensitizing agent, is dissolved and removed so that it can be used repeatedly. The aforementioned cleaning nozzle 12 is used at this time. The particle level such as the size and number of dust is measured, and when the particle level is lower than an intended target value, the discharge nozzle 7
The wafer 13 is moved upward by the moving mechanism, and the application to the wafer 13 is performed.

The coating method using the coating apparatus provided with the evaluation apparatus of this embodiment is executed according to the flowcharts shown in FIGS. First, the discharge nozzle is moved above the monitor substrate (1). Next, a resist liquid is applied on the monitor substrate from a discharge nozzle to form a resist film (2). Next, the resist film on the monitor substrate is irradiated with light from a light source such as a semiconductor laser (3). Next, the transmitted scattered light transmitted through the resist film from the back side of the monitor substrate is received by a light receiving element or the like (4). The particle level such as the size and number of dust in the resist film is detected based on the scattering state of the received light (5). If the particle level in the resist film is higher than the reference, that is, if the number of particles is higher than a certain reference, the liquid is changed without using the resist liquid in the resist tank (6). If the particle level is lower than the reference, the discharge nozzle is moved onto the wafer as the sample (7). Then, a resist liquid is applied to the wafer from a discharge nozzle to form a resist film (8). As described above, in the present invention, since the system always checks the resist solution before applying the resist, a stable resist solution can be supplied. As a result, for example, a wiring pattern with few defects can be provided. -Can be formed at any time.

FIG. 5 is a characteristic diagram showing the relationship between the number of dusts (pieces) on or in a resist film and a short circuit (short) between wirings electrically measured. The vertical axis represents the non-defective rate (%), and 100% means that there is no short circuit. The horizontal axis represents the number of particles of 0.3 μm or more in a certain area (in this case, the entire area of the resist film on a 6-inch diameter silicon wafer). The wiring measured here is made of phosphorus-diffused polysilicon having a wiring interval and a wiring width of about 0.8 μm. As the wiring, a wiring formed on a silicon semiconductor substrate is used. The forming method is as follows. A polysilicon film diffused with phosphorus is formed on the silicon semiconductor substrate. On this, a resist film is formed by the method according to the above embodiment. Thereafter, the resist film is patterned to form a resist pattern. Then, the polysilicon film under the resist pattern is etched. Finally, the resist pattern is peeled off to form a wiring pattern made of polysilicon. Electrical measurement is performed on this wiring pattern. From this measurement result, it can be seen that the larger the amount of dust, the higher the short circuit occurrence rate. In particular, when the number of dusts on the resist film exceeds 100, the yield rate falls below 60%. In this embodiment, the wiring pattern having the wiring width of about 0.8 μm has been described. The size of the target dust at that time is about 0.
Although it is 3 μm or more, when the miniaturization of the semiconductor device further advances and the wiring width becomes narrower than 0.8 μm, a short circuit accident cannot be prevented at this level, and the size of the target dust is reduced to about 0.1 μm or less. Need to be done.

Next, a second embodiment will be described with reference to FIG. The figure is a cross-sectional view of the resist supply system,
It can be connected to the coating apparatus of the previous embodiment. The resist supply system shown in FIG. 2 is characterized in that the resist liquid is pushed out from the discharge nozzle by a controlled pump, whereas in this embodiment, the pump is not used and gravity is used. is there. As shown,
The resist tank containing the resist solution 1 is at the top and is connected to the discharge nozzle 7 at the bottom by the pipe 2. The pipe 2 is provided with a stop valve 6 for controlling the discharge of the resist solution. In this supply system, the amount of materials that come into contact with the resist solution, such as pumps, valves, and manufacturing containers, used in the supply system as shown in FIG. 2 can be considerably reduced. These contact materials generate rigid dust due to the contact, and their presence is not preferable in the field of utilizing resist. Therefore, in this embodiment, since the rigid dust can be considerably reduced, it is hardly considered that the resist liquid is evaluated as unusable due to this.
Of course, dust can be removed by attaching a filter or the like, but it is not necessary to attach it especially since the contact material increases.

In the above-described embodiment, a laser beam using a semiconductor laser having a wavelength λ of 780 nm is used as the light source 11, but it is not necessary to rely solely on the laser beam. The wavelength is not limited, and any electromagnetic wave may be used. The light source can be moved or the light beam can be reflected. It is most effective to transmit the irradiation radiation to the monitor substrate.

[0013]

According to the present invention, the particle level in the resist is checked before coating on a substrate such as a wafer, so that a resist solution having a desired particle level can be used. A uniform and stable resist film can be obtained. In addition, since the particle level can be monitored, a simple resist supply system can be provided that does not use pumps, filters, valves, and the like that may generate dust from themselves.

[Brief description of the drawings]

FIG. 1 is a sectional view of a resist coating apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of the present invention and a conventional resist supply system.

FIG. 3 is a coating process diagram of the resist coating method of the present invention.

FIG. 4 is a coating process diagram of the resist coating method of the present invention.

FIG. 5 is a characteristic diagram showing the dependency of the yield rate on the number of dusts in a resist film.

FIG. 6 is a configuration diagram of a resist supply system used in a second embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 resist solution 2 pipe 3 pump 4 filter 5 suck back valve 6 stop valve 7 discharge nozzle 8 discharge port 9 monitor substrate 10 light irradiation unit (light source) 11 scattered light detection unit 12 cleaning nozzle 13 sample (wafer) 14 spin chuck 15 Spin motor 16 Drain 17 Coat cup

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/027

Claims (6)

(57) [Claims] A means for supplying a resist solution; a transparent monitor substrate on which the resist solution is applied; and a resist film formed from the resist solution on the monitor substrate, which is irradiated and transmitted through the monitor substrate. And a light detector for detecting light passing through the monitor substrate. 2. The resist evaluation apparatus according to claim 1, wherein the means for supplying the resist liquid has a means for allowing the resist liquid to freely fall on the monitor substrate. 3. The resist evaluation apparatus according to claim 2, wherein the monitor substrate is inclined with respect to the horizontal. 4. A means for supplying a resist solution, a transparent monitor substrate on which the resist solution is applied, and a resist film formed on the monitor substrate formed from the resist solution is irradiated and transmitted through the monitor substrate. A resist evaluation device having a light source that generates light and a photodetector that detects light transmitted through the monitor substrate; a sample support table that supports a sample to which the resist solution is applied; and a unit that supplies the resist solution. A device for moving on the monitor substrate or the sample. 5. The sample supporter receives an excess resist solution generated from the means for supplying the resist solution, and is further placed in a coater for discharging the excess resist solution. The resist coating device according to claim 4, wherein the monitor substrate of the resist evaluation device is disposed in the tar cup. 6. A step of applying a resist liquid on a surface of a transparent monitor substrate to form a resist film; a step of irradiating the resist film with light; and a step of applying light irradiating the resist film to the monitor substrate. Detecting from the back side, counting the number of particles of the resist film from the detected scattering state of the light, the resist applied to the monitor substrate only when the number of particles of the resist film is equal to or less than an allowable value. Applying the same resist solution as the solution onto the sample to form a resist film.