JPS623971B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing device and a developing method, and particularly to a device for developing a positive resist and a developing method using the same.

In recent years, as the development of VLSI has progressed, positive resists have been used as resists for miniaturization. Positive type resists have a feature of higher resolution than negative type resists, and are therefore often used for pattern formation of 1 to 2 μm.

Positive resists are made by synthesizing novolac resins with quinone diazide resins, and have trade names such as Shipley's ``AZ-1450,'' Kodak Co., Ltd.'s ``809,'' and Tokyo Ohka Co., Ltd.'s ``800.'' These are all photodegradable resists, and only the areas irradiated with ultraviolet light dissolve in the developer.

In general, compared to a photopolymerizable negative resist, the development speed of a positive resist requires 2 to 4 times the development time for the same resist film thickness. On the other hand, LSI
In the process, the photolithography process is also automated, including resist coating, pre-bake, development,
Automatic equipment is used that performs the post-bake process in-line. These automatic devices are devices that continuously process semiconductor substrates (wafers) one by one, but when developing positive resist patterns using these devices, several problems occur, as described below. It cannot be said that it is completely automated.

As a method of bringing the developer into contact with the exposed resist surface, a spray gun or a nozzle is used to spray the developer onto the resist surface. According to this method, the pressure of the sprayed developer varies within the sprayed area of the spray gun, or the particle size of the mist similarly varies, resulting in non-uniform development speed on the semiconductor substrate. , the development pattern width changes. In areas where the pressure of the developer is strong or where the particle size is coarse, development proceeds quickly and the width of the pattern to be left becomes narrower. In addition, in the case of a spray gun, if you try to form a spray that covers the entire main surface of a semiconductor substrate with a diameter of 10 cm, for example, you will need a large device and the development time will have to be significantly lengthened. , this method is not practical. Therefore,
The inventor considered improving the uniformity of the spray by making the spray from the spray gun into an elliptical shape, covering half of the semiconductor substrate, and rotating the semiconductor substrate. As mentioned above, since the spray pressure distribution of the spray gun is non-uniform, it has been impossible to perform uniform and highly accurate development.

Another method is to stop the semiconductor substrate and
There is a method of developing by dropping developer solution from a nozzle and accumulating the developer solution on the semiconductor substrate due to surface tension, but as semiconductor substrates become larger than 10 cm in diameter, the first development drop to the last development drop increases. There will be a difference in the time it takes. For example, nozzle diameter 2
mm, it takes about 5 seconds for a semiconductor substrate with a diameter of 10 cm, and this time difference causes a difference in the developed pattern. In addition, if you increase the nozzle diameter or increase the dropping speed in order to shorten the dropping time, the pressure of the developer falling onto the semiconductor substrate will be increased between the center of the semiconductor substrate where it is dropped and the outer edge of the semiconductor substrate. Unlike,
The difference appears as a variation in pattern width.
The amount of variation in the width of these developed patterns reaches as much as 0.2 to 0.6 .mu.m, and for a super LSI designed with a pattern width of 2 .mu.m, the amount of variation reaches 10 to 30%, which is not practical. An alternative and more reliable development method is the immersion development method that performs batch processing, but in the case of an in-line development device,
This method has not been put to practical use because it increases the complexity of the device.

FIG. 1 shows a part of an automated developing device that is conventionally and widely used. In this device, a wafer mounting table (wafer chuck) 1
Semiconductor substrates 2 are placed on top one by one, and the wafer mounting table 1 is rotated at a speed of 10 to 2000 rpm, and while the semiconductor substrates 2 are being rotated, a solvent (developer) is sprayed by a spray gun 3. That is, in order to constantly apply fresh solvent 4 to the surface of the semiconductor substrate 2, development is performed while also rotating the semiconductor substrate 2. However, when the photosensitive resin is positive type, the development speed is extremely slow, so if development is performed by rotating it like a negative type resist, the amount of solvent used will be significantly large, and if the photosensitive resin is positive type, the substrate 2 Due to the extremely poor adhesion, the developed pattern may be deformed depending on the spray condition of the spray gun 3.
Or it may be blown away, reducing the yield of pattern formation.

For this purpose, in the usual method, the rotation of the wafer chuck is stopped and the solvent is dripped from a spray gun or nozzle while the wafer chuck is stationary, and development is carried out using the solvent 4 that remains due to the surface tension of the substrate surface. Ta.

As shown in Figure 1, if you look at the cross section of the solvent left behind due to surface tension, the amount of solvent is small around the substrate;
They are increasing in number near the center. For this reason, fresh solvent does not constantly come into uniform contact with the mask-exposed photosensitive resin, and the developed pattern around the substrate has a smaller pattern size than the area near the center.
Alternatively, a situation occurred where development was not completely completed. All of these phenomena reduce the yield.

The present invention eliminates the above-described drawbacks that have conventionally occurred and provides a developing device and a developing method that can obtain a uniform developed pattern within a substrate.

FIGS. 2 and 3 each show the structure of the main parts in an embodiment of the developing device of the present invention.

In the apparatus shown in FIG. 2, a wafer 11 having a resist layer to be developed is vacuum-adsorbed onto a wafer mounting table 12. As shown in FIG. A ring-shaped frame 13 is arranged around the periphery of the wafer mounting table 12. This frame 13 has a diameter larger than the diameter of the wafer 11, and is also equal to or thicker than the thickness of the wafer 11. This frame 13 is constructed separately from the wafer mounting table 12, and by changing the position of the wafer mounting table 12 or the frame 13 in the direction of the arrow, the frame 13 comes into contact with the wafer mounting table 12. Or leave. Further, the wafer mounting table 12 is rotationally driven by a drive device (not shown) such as a motor. Further, the developer is supplied from the nozzle 15.

The apparatus shown in FIG. 3 includes a wafer mounting table 12 having a taper that tapers downward;
A frame 16 that has a tapered hole that engages with the frame and has a peripheral edge that stands up in the vertical direction.
and has. The inner diameter of the upright portion on the peripheral edge of the frame 16 is larger than the diameter of the wafer 11, and its height is equal to or larger than the thickness of the wafer 11. Then, an O-ring 17 is interposed in the portion where the wafer mounting table 12 and the frame 16 engage,
Prevents liquid leakage. Of course, this is not particularly necessary if the wafer mounting table 12 and the frame 16 are configured to be in close contact with each other to the extent that no liquid leakage occurs. By moving the wafer mounting table 12 or the frame 16 up and down in the direction of the arrow 14, the positional relationship between the two becomes that of the mounting table 12 and the frame 16' shown by the broken line.

Next, the developing method of the present invention will be explained.

FIG. 4 is a process diagram of an example using the apparatus shown in FIG. 2.

A wafer 11 which has been exposed to a mask and has a resist to be developed is placed on a wafer mounting table 12 and subjected to vacuum absorption (FIG. 4a). In this state, the frame 13 is located above the wafer mounting table 12. Wafer 11 is wafer mounting table 1
2, the frame 13 comes into contact with the wafer mounting table 12 and becomes the state shown in FIG. 4b, and the nozzle 15
The developer 20 is dropped onto the upper surface of the wafer mounting table 12 surrounded by the frame 13. Dropped developer 2
1 fills the area of the recess formed by the frame 13 and the wafer mounting table 12 (FIG. 4c). developer 20
is up to the height of the frame 13, that is, the wafer 11
Fill to a sufficient depth for immersion. In this state,
The resist is developed. When the predetermined development time has elapsed, the frame 13 is separated from the wafer mounting table 12, and
When the wafer mounting table 12 is rotated, the wafer 1
The excess developer on the surface of the developer 1 is scattered as indicated by the reference numeral 21' in FIG. 4d. Further, by dropping a rinse liquid onto the resist of the wafer 11 from the nozzle 15 and processing it in the state shown in FIG. 4d, the developing process can be completed. Of course, a nozzle other than the nozzle 15 may be used for dropping the rinse liquid. Through such operations, the resist on the wafer is developed.

FIG. 5 shows a development process using the apparatus shown in FIG. First, when the frame 16 is at the position 16' shown by the broken line in FIG. The wafer is brought into contact with the wafer mounting table 12 to obtain the state shown in FIG. 5a.

A developer is dripped from the nozzle 15 and the frame 1 is
6 and the wafer mounting table 12 (FIG. 4b). The resist on the mask-exposed wafer 11 is developed while being filled with the developer 31. Note that the amount of developer 31 depends on the frame 16.
You can choose freely depending on the height. This also applies to the frame having the structure shown in FIG.
After a predetermined period of time has passed and the development is completed, the frame 16
is lowered, the wafer mounting table 12 is rotated, and the developer 31 is scattered (FIG. 4c). Next, the rinsing liquid is dripped onto the wafer 11 from the nozzle 15,
Completely remove developer. Thereafter, the rotation of the wafer mounting table 12 is stopped (FIG. 4d), and the developed wafer 11 is obtained.

FIG. 6 shows a more practical configuration example of the present invention. FIG. 6a shows a structure in which a plurality of nozzles 39 are formed around the frame 16, and these plurality of nozzles 39 are connected by holes 40 connected inside or outside the frame 16. . The nozzle 39 is formed to open toward a recess area surrounded by the frame 16 and the wafer mounting table 12. Further, the hole 40 is connected to a supply pipe 41 in order to cause the developer to flow out from the nozzle 39.
is connected to. That is, when a pressurized developer is supplied from the supply pipe 41, the developer fills the hole 40 and at the same time flows out 42 into the concave region through the plurality of nozzles 39 provided inside the frame 16, and , and immersion development of the wafer 11 is performed.

FIG. 6b shows a structure in which a plurality of nozzles 49 are provided on the flat surface of the frame 16. That is, the developer is supplied to the supply pipe 51 provided on the lower side of the frame 16.
from the hole 50 provided in the frame 16,
Furthermore, it is guided to a plurality of nozzles 49 and flows out. In the figure, the hole 50 is provided inside the frame 16, but the same effect can be obtained even if a tubular body is provided outside the hole 50.

A typical example where such a configuration is applied to the apparatus shown in FIG. 2 will be explained using FIG. 7.

In FIG. 7a, a frame 13 is provided with a plurality of nozzles 59 for causing liquid to flow out.The frame 13 is hollow, and the nozzles 59 are provided toward the inside of the frame 13. It is being Reference numeral 61 is a pipe for supplying liquid to the hollow portion 60 of the frame 13, and when the developer is pressurized and flows into the supply pipe 61, it flows out through the hollow portion 60 and from the plurality of nozzles 59. do. Although the frame 13 is shown to have a circular cross-sectional shape, it may have a square cross-section. FIG. 7b shows a plurality of nozzles 69
is provided on the flat surface of the wafer mounting table 12. The hole 70 connecting the nozzle 69 and the supply pipe 71 for supplying the developer may be provided in the wafer mounting table 12 as shown in the figure, but it is also possible to use a tube separate from the mounting table 12. It is okay to do so.

Next, the effects of the present invention will be described.

In the present invention, a sufficient amount of developing solution can be supplied to the substrate having the exposed resist by the recessed area formed by the wafer mounting table and the frame, and furthermore, immersion development can be performed, so that uniform development can be performed. A stable developed pattern can be formed. Furthermore, compared to development by conventional spray methods, etc., this method is economical because it does not require more developer than necessary. In addition, in the present invention, since the developer can be supplied without applying pressure to the surface of the substrate having the photosensitive resist, dimensional unevenness in the width of the developed pattern due to the pressure applied when dropping or spraying the developer can be prevented. There is no risk of this occurring.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining an example of a conventional developing method, FIGS. 2 and 3 are sectional views of essential parts showing a typical embodiment of the developing device of the present invention, and FIGS. 4 a to d 5 a to d are process diagrams of an embodiment of the developing method of the present invention, and FIGS. 6 a, b and 7 a, b are sectional views showing other embodiments of the developing device of the present invention, respectively. It is. 11...Wafer, 12...Wafer mounting table,
13... Frame body, 15... Nozzle, 16... Frame body,
31... Developer, 39... Nozzle, 40... Hole,
41...pipe, 49...nozzle, 50...hole,
51...Pipe.

Claims (1)

[Scope of Claims] 1. A wafer mounting table on which a wafer is to be placed; a recess that is separably placed on the wafer mounting table, is larger in diameter than the wafer, and is equal to or deeper than the thickness of the wafer; Each wafer is provided with a frame for surrounding the wafer to form a region, and a means for supplying a developer to a recessed region formed by the frame and the wafer mounting table. A developing device. 2. The developing device according to claim 1, wherein the frame is movable up and down with respect to the wafer mounting table. 3. The developing device according to claim 1, wherein the developer supplying means is a nozzle placed above the recess, or a nozzle provided on the frame or the wafer mounting table. 4 Place the wafers to be developed at the specified positions on the wafer mounting table, one per wafer mounting table.
wafers, and then contacting the wafer mounting table in a separable manner with a frame larger than the diameter of the wafer and having a thickness equal to or higher than the wafer so as to surround the wafer; a step of supplying a developer into a recessed area formed by the wafer mounting table and the frame; after development, separating the frame and the wafer mounting table; and further placing the wafer on the wafer mounting table; A developing method comprising the step of rotating while being held.