JPS63184330A - Baking device for photoresist - Google Patents

Abstract

PURPOSE:To set temperature distribution in a wafer surface arbitrarily, and to equalize the pattern size of a semiconductor device in the wafer surface by concentrically dividing, separating and disposing a plurality of ring-shaped hot plates having different diameters and mounting severally driven heat sources to each hot plate. CONSTITUTION:A plurality of ring-shaped hot plates 11, 12...1n having different diameters are divided, separated and arranged concentrically, severally driven heat sources 21, 22...2n are set up to respective hot plate 11, 12...1n, a plurality of the hot plates 11, 12...1n having different diameters are brought into contact with a wafer 3, the temperatures of each heat source 21, 22...2n are controlled, and the wafer 3 is heated by the hot plates 11, 12...1n. Since the sensibility of a photoresist generally changes by the temperature of pre-baking, the size of a resist pattern is distributed in the wafer by varying the sensibility of the resist in the wafer, thus equalizing size after etching.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to prebaking of photoresists used in semiconductor manufacturing processes, and particularly to a hot plate type baking apparatus.

[Conventional technology]

Conventional photoresist pre-baking methods using hot plate equipment aim to evaporate the solvent contained in the photoresist, and the wafer is heated completely or partially on the back side of the wafer so that the temperature distribution within the wafer is uniform. A hot plate in contact with the wafer was kept at a specific temperature to adsorb the wafers, but each hot plate was kept at a uniform temperature by a single heat source.

[Problem that the invention seeks to solve]

In the above-mentioned conventional pre-bake method using a hot plate device, the sensitivity of the photoresist is always maintained uniformly within the wafer surface, but this brings about the following drawbacks in the semiconductor manufacturing process. That is, one step of photolithography using a photoresist in a semiconductor manufacturing process involves steps roughly classified into two types as shown below. The first is when a resist base is selectively etched using a photoresist pattern formed by lithography, and the second is when ions are implanted using the formed photoresist pattern as a mask. In the former case, the pattern obtained is strongly influenced by the etching properties, while in the latter case only the pattern of the photoresist is affected by the pattern (ion implantation region).
Determine.

In order to form a large number of semiconductor devices with the same characteristics on a wafer, in the latter case, it is necessary to make the photoresist pattern dimensions uniform within the wafer surface, but in the former case, it is necessary to make the pattern dimensions of the photoresist uniform within the wafer surface. The dimensions after etching must be uniform.

In the conventional photoresist pre-baking method, the sensitivity of the photoresist within the wafer plane is always uniform, so the resist pattern dimensions within the wafer plane are uniform, but when the photoresist pattern involves selective etching of the underlying layer, The etched pattern has the disadvantage that it causes dimensional variations within the wafer surface due to etching characteristics.

An object of the present invention is to provide a photoresist baking device that can arbitrarily set the temperature distribution within the surface of a sea urchin.

[Differences between the invention and the prior art]

In contrast to the pre-bake method using the conventional hot plate apparatus described above, the hot plate pre-bake apparatus of the present invention has a heat source shaped to provide a concentric temperature distribution within the wafer surface, thereby improving the sensitivity of the resist on the wafer. It is possible to have a distribution within. By changing the sensitivity of this resist within the wafer, the resist pattern dimensions can be distributed within the wafer and the dimensions after etching can be made uniform. By making the temperature distribution of the hot plate uniform, the resist pattern dimensions can be made uniform. As described above, the present invention has an original content in that the prebaking temperature of the photoresist can be freely distributed concentrically within the wafer.

[Means for solving problems]

The present invention is a baking device that heats photoresist using a hot plate in a semiconductor manufacturing process, in which a plurality of ring-shaped hot plates with different diameters are arranged concentrically and independently, and each hot plate is individually driven. This is a photoresist baking device characterized by being equipped with a heat source.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

In the semiconductor manufacturing process, when the base of the resist is selectively etched using a photoresist pattern formed by lithography, the pattern dimensions after etching will vary depending on the etching characteristics even if the pattern dimensions of the photoresist are uniform within the plane. Due to this influence, especially when dry etching is performed when the base is PolySi (polycrystalline silicon), the wafer exhibits a dimensional distribution symmetrically about the wafer center, as shown by the solid line in FIG. If this is not due to an abnormality during the process, but is due to an essential factor unique to the process, such as the in-plane variation in etching rate peculiar to the etching apparatus shown by the dotted line in FIG. If the distribution is opposite to the dimension after etching as shown in the figure, they will cancel each other out, and the pattern dimension of the resist base after etching can be made uniform within the wafer surface as shown in FIG.

Incidentally, the sensitivity of a photoresist generally changes depending on the prebaking temperature as shown in FIG.

Therefore, if the prebake temperature can be distributed within the wafer as shown by the solid line in Figure 3, the resist dimensions within the wafer plane can be distributed as shown in Figure 7, and the etching dimensions can be distributed within the wafer plane as shown in Figure 8. It is thought that it will be uniform.

As shown in FIGS. 1 and 2, a plurality of ring-shaped hot plates 11, 1 . □
...1n heat sources 2□, 22...2 individually driven
A plurality of hot plates 1□112...In of different diameters are brought into contact with the wafer 3, and each heat source 21, 2□...
The wafer 3 is heated by hot plates 11°, 12, . . . 1n while controlling the temperature of 2n.

(Example 1) As mentioned above, the sensitivity of photoresist generally changes depending on the pre-bake temperature as shown in Fig. 5, so if the pre-bake temperature is distributed within the wafer as shown by the solid line in Fig. 3, the wafer The in-plane resist dimensions are distributed as shown in FIG. 7, and the etching dimensions can be made uniform within the wafer plane as shown in FIG. 8. Therefore, in the case of this embodiment, the ring-shaped hot plates 11...1 are arranged concentrically.
Set the temperature of the center hot plate 11 at about 80°C, and set the temperature of each hot plate 12...1n toward the outer periphery.
The set temperature is increased to form a temperature distribution as shown by the solid line in FIG.

(Example 2) Next, Example 2 will be described. When a photoresist pattern is formed and ions are implanted into a mask, the ion implantation area is determined only by the dimensions of the resist pattern. In this case, it is necessary to make the temperature distribution within the wafer surface constant as shown by the dotted line in FIG. 3, and to make the resist sensitivity within the wafer surface uniform. In this embodiment, the temperatures of the hot plates 1□ to 1n of the present invention may be set to the same temperature. Thereby, the resist dimensions within the wafer surface can be made uniform, and the ion implantation region can be made uniform within the wafer.

〔Effect of the invention〕

As explained above, the present invention allows the set temperature of hot plates with different diameters inside and outside to be freely changed in a concentric manner. This has the effect of making the pattern dimensions of semiconductor devices uniform.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a photoresist hot plate pre-baking device of the present invention, FIG. 2 is a longitudinal sectional view thereof, and FIG. 3 is a temperature distribution diagram showing an example of an embodiment using the pre-baking device of the present invention. FIG. 4 is a hypothetical etching rate distribution diagram, FIG. 5 is a diagram showing the change in general resist sensitivity due to pre-bake temperature, and FIG. A diagram showing the distribution of resist sensitivity; FIG. 7 is a diagram showing the in-wafer distribution of resist pattern dimensions in the example shown in FIG. 6; FIG. 8 is an example of the embodiments shown in FIGS. 3 to 7. FIG. 4 is a diagram showing the distribution of pattern dimensions within the wafer surface after etching.

Claims (1)

[Claims] (1) In a baking device that heats photoresist using a hot plate in a semiconductor manufacturing process, a plurality of ring-shaped hot plates with different diameters are arranged concentrically and independently, and each hot plate is individually driven. A photoresist baking device characterized by being equipped with a heat source.