JPS6053305B2 - Development method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing method, and in particular to a method for developing a semiconductor wafer coated with a positive photosensitive resin in a photoetch process during semiconductor manufacturing more uniformly over the entire wafer and at a lower cost. The purpose is to

In the semiconductor manufacturing process, the photoetch process means applying a photosensitive resin (hereinafter referred to as photoresist) to one main surface of the semiconductor → soft bake → mask alignment exposure → development → hard bake.

Initially, the development process adopted the so-called ``dip method'' in which the entire wafer was immersed in a developer and a rinse solution.
Recently, with the spread of automatic developing equipment, the so-called "spin-spray method" in which developer is sprayed while rotating the wafer has become popular.
' has become more commonly used.

The conventional method is shown below. In FIG. 1, a semiconductor wafer 1
The wafer 1 is fixed by a spinner head 2 using a vacuum chuck method, and the wafer 1 is rotated by a rotating device 3 at, for example, 500°, p, m for about 60 seconds, and a dew-like developer 5 is jetted from a developer jetting nozzle 4.

Next, a rinsing solution of about 6@PE is dispensed in the same format as the above-mentioned developer. And finally, wafer 1 is heated to 2000rpm~500rpm.
Rotate about 2 times at 0 rpm to dry the rinse solution.
This is the normal ``spin-spray'' development method. Incidentally, the mist of the developing solution and the rinsing solution is generated by a commonly used method based on Bernoulli's principle. According to the studies of the present inventors, the problem with this method is that the developing solution continues to be ejected for 6 hours during development.

In particular, since the development reaction of positive type photoresists proceeds more slowly than that of negative type photoresists, there are areas on the wafer 1 that are hit by the atomized developer 5 and areas that are not hit.
Since the wafer 1 is constantly rotating during development, a centrifugal force acts on the developer on the wafer 1, resulting in excess or deficiency of development at the center and edges of the wafer 1. This development becomes more noticeable as the size of the wafer 1 increases, as has recently been the case. FIG. 2 is a diagram previously proposed by the present inventor in Japanese Patent Application No. 53-8744.

If this method is used, extremely uniform development can be achieved, but the cost is undeniable because the apparatus becomes complicated and, as in the case of FIG. 1, an expensive developing solution is continuously dispensed for about 6 W. On the other hand, as shown in Fig. 3, a method has been considered in which the developer 9 is brought into contact with the wafer 1 in a "drip" manner from the nozzle 8 to cause a development reaction, but it is extremely difficult for the developer to get around to the back surface of the wafer 1. Intense and “dripping”
Since this method requires a larger amount of developer than those shown in FIGS. 1 and 2, the cost is high and there are many problems. The present invention has been made as a result of the above ideas, and proposes a method that shortens the developer supply time, is low in cost, and can obtain a uniform developed pattern.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

In FIG. 4, the atomized developer 11 is irradiated onto the surface of the wafer 1 from a jet nozzle, so that the entire surface of the wafer 1 is wetted. At this time, if the wafer 1 is rotated at a low speed by the rotating device 12, the entire surface will be wetted more quickly. A suitable rotation speed is 100 r'Pm or less. If the speed is about 300 rpm or more, most of the developer will scatter, and if the supply of the atomized developer 11 is then stopped, the amount of developer remaining on the wafer 1 will be very small, and the developing ability will drop. Therefore, in the present invention, FIG.
As shown in FIG. 4, the atomized developer is supplied onto the surface of the wafer 1 by rotating the wafer at a predetermined rotational speed, and when this supply is stopped, the result is as shown in FIG. 4b. Then, the developer 13 forms a layer of 2 to 3 m and stays uniformly on the wafer 1 due to surface tension. In the present invention, development is performed in this state, for example. At this time, it is effective to rotate the wafer 1 at a low speed (approximately 50 rpm) in order to promote the development reaction, but the optimal state shown in FIG. 5a is as shown in FIG.
Do not rotate the wafer at such a high speed that it starts to overflow and decreases at the center of the wafer 1. This stoppage of the development supply is repeated several times, and then the rinsing step is started. The centrifugal force applied to the developer on the wafer 1 depends on the wafer size (for example, 2 inches, 3 inches, 5 inches), and the wafer size. Since it is related to the rotation speed of the wafer and the rotation speed of the wafer, it is necessary to optimize the rotation speed depending on the wafer size. Incidentally, the method of supplying the developer may be a dropping method in which the developer is dropped using another pump as described above. However, in this case, do not supply the developer in a mist form!
Therefore, a protective cover for preventing the atomized developer from scattering is not necessarily required. A general comparison of the conventional developing method and the developing method of the present invention is as follows.

(1) The conventional development method is 1 development (500 to -100
0 rpm 50-60 seconds) → 2 rinses (500-1000
r'Pm5O~60 seconds) → 2 drying (2000~5000
A step called rpm2(8) is taken.

On the other hand, (2) the developing method of the present invention is, for example, 1 developer supply (10 & Pm, W seconds) → 2 developer supply stop (0 to 50
rpm, ratio seconds) → 3 Developer supply (10pm, 1@→7 Developer supply stop (0 to 50 rpm, 258) Rewas (30
The process is as follows: 0 rpm, 4 fish) → drying (2 (1) αPm, 2 (8)).

In the present invention, the state in which the developer is present on the wafer, that is, the total development time is approximately the same as the development time of the conventional development method.

The cycle of development → developer supply stop I was performed twice in the above 2, but this means that the developer used in the development process of 1 → 2 is discarded (this is naturally discarded by entering the process of 3). The purpose of this method is to supply a new developing solution (the developing ability naturally deteriorates as developing reactions accumulate) to produce an extremely good developing reaction. It doesn't have to be adopted.
Now, in the present invention, since the developer is constantly supplied during development and the wafer is not rotated as in the conventional case, uniform development can be performed.

That is, conventionally, during development, the developer is constantly being hit on the wafer, and the developer is always in a disordered state on the wafer, and a large centrifugal force is exerted on the developer due to the rotation of the wafer. Therefore, it is difficult for the developer to become uniform on the wafer surface, resulting in unevenness in the development process. Furthermore, in the conventional method, since the developer is constantly in motion, the developing ability of the resist and the like cannot be fully utilized. However, in the present invention, after covering the wafer with the developer, development is performed while the wafer is stopped or rotated at low speed, so that sufficient and uniform development can be performed. For example, when a semiconductor wafer coated with a positive photosensitive resin is developed according to the present invention, an extremely uniform developed pattern can be obtained. If the reference dimension of LS)I is 2 to 3 μm (the smaller the design dimensions of an integrated circuit, the more dimensional accuracy is required), the variation can be sufficiently suppressed to within 10%. The method of the present invention becomes more effective as the wafer size increases. Further, in the present invention, since the developer supply time is less than half that of the conventional method, the cost required for the extremely expensive positive photoresist developer can be halved in the mass production process. Therefore, the present invention can be said to be an extremely effective method for large-diameter wafer mass production processes using positive resists, which will be essential for future LSI manufacturing processes.

[Brief explanation of the drawing]

Figure 1 is a diagram showing a conventional semiconductor wafer development method;
The figure shows a developing method proposed by the present inventor, FIG. 3 shows another conventional developing method, and FIGS. 4A and 4 b show a semiconductor wafer developing method according to an embodiment of the present invention. Schematic diagram showing,
FIGS. 5A and 5B are diagrams showing the state of the developer on the wafer in the method of the present invention. DESCRIPTION OF SYMBOLS 1...Semiconductor wafer, 10...Developer jet nozzle, 11...Atomized developer, 12...
...Rotating device, 13...Example of state of developer on wafer.

Claims (1)

[Scope of Claims] 1. A developer is applied onto the main surface of the object to be developed while rotating the object to be developed, and when the developing solution sufficiently covers the main surface with its surface tension, the development is performed. supply or stop the liquid,
After that, the developing method is characterized in that the object to be developed is kept stationary or rotated at a low rotational speed that does not allow the developer to scatter away from the main surface, and then moves to a rinsing step. 2. The developing method according to claim 1, wherein the object to be developed is a semiconductor substrate whose main surface is coated with a positive photosensitive resin.