JPH03268419A - Heat treatment method and equipment - Google Patents

Abstract

PURPOSE:To reduce a cost, making a photolithography process for removing an insulating film in the outer periphery of a wafer unnecessary, by bringing a hot plate and the outer periphery of the wafer in non-contact with each other and making the film quality of the insulating film in a non-contact region different from the one in a contact region, when baking the insulating film through putting the wafer on the hot plate. CONSTITUTION:When baking an insulating film 3, putting a wafer 2 to which the insulating film 3 is applied on a hot plate 4, at least a part of the outer periphery of the wafer 2 is brought in the state of non-contact with the hot plate 4. In the wafer 2, the difference between the film qualities of the insulating film 3 in a region (B) and a region (A), where the wafer 2 is in contact and in non-contact with the hot plate 4 respectively, is made to generate. The quality of the insulating film 3 in the region (A), where the wafer 2 is in non-contact with the hot plate 4, comes into an unstable state in comparison with the insulating film in the region (B). Therefore, for example, in a developing process and an etching treatment process for forming an integrated circuit after a heat treatment, the insulating film 3 in the region (A) can be removed together with a resist. Thereby, the reliability and the yield of an integrated circuit device can be improved, and its production cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat treatment technique, and particularly to a heat treatment technique for baking an insulating film coated on a semiconductor wafer (hereinafter simply referred to as a wafer).

[Conventional technology]

In order to stabilize the film quality of insulating films such as photoresist and surface protection films coated on wafers, such as polyimide, heat treatment technology in which the wafer is placed on a hot plate and the insulating film is baked is described in Japanese Patent Laid-Open No. 61-28152
There is a description in Publication No. 7.

The hot plate in the above conventional heat treatment equipment includes:
A planar heating element was provided to make the temperature of the hot plate uniform, and the heating surface of the hot plate was designed to be larger than the diameter of the wafer.

To bake polyimide coated on a wafer using such a heat treatment device, for example, polyimide is first spin-coated onto the wafer using a spinner coating method, and then the wafer is placed on a hot plate. Then, heat treatment is performed while the material is fixed by vacuum suction. By the way, since polyimide is applied by spin coating, it is applied to the entire main surface of the wafer, but the polyimide on the outer periphery of the wafer is
When a wafer is fixed with a clamp claw, it may peel off and become a contaminant, or it may bulge and cause the wafer to crack during back grinding, and the wafer may come into contact with the probe bin during probe inspection and adhere to it. This may cause problems such as making it easier to conduct erroneous tests. Therefore, in the past, after baking the polyimide on the wafer using a heat treatment device, a method was used to remove the polyimide from the outer periphery of the wafer.
It was necessary to add an IJ Sogelahuie process in addition to the photolithography process that is used to form integrated circuits.

[Problem to be solved by the invention]

However, the present inventor found that the above conventional technology has the following problems.

That is, for example, like a surface protective film such as polyimide,
Depending on the insulating film coated on the wafer, it may not be possible to perform edging to remove the undried insulating film that has wrapped around the wafer's outer periphery to the back side. When placed on the hot plate of a heat treatment equipment, the heated surface of the hot plate is larger than the diameter of the wafer, so the undried insulating film that has wrapped around the back side of the wafer will adhere to the heated surface of the hot plate, causing contaminants. In addition, there is a problem in that the adhered and solidified insulating film causes a transport error when the wafer is transported.

Furthermore, in addition to the photolithography process for forming integrated circuits during the manufacturing process of semiconductor integrated circuit devices, a photolithography process for removing the insulating film on the outer periphery of the wafer is required after the insulating film is applied. There is a problem in that the number of man-hours and manufacturing cost for manufacturing a semiconductor integrated circuit device increases due to processing steps such as mask creation, exposure, and development.

The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a technique that can improve the reliability and yield of semiconductor integrated circuit devices.

Another object of the present invention is to provide a technique that can reduce the number of manufacturing steps and manufacturing costs of a semiconductor integrated circuit device.

The above and other objects and novel features of the present invention will become apparent from the description of the specification and the accompanying drawings.

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

That is, the invention as set forth in claim 1 provides that when a wafer coated with an insulating film is placed on a hot plate and the insulating film is baked, the hot plate and at least a part of the outer periphery of the wafer are brought into contact with each other. This heat treatment method produces a difference in the film quality of the insulating film between the hot plate contact area and the non-contact area of the wafer.

The invention according to claim 2 is a heat treatment apparatus having a hot plate for baking an insulating film applied to a wafer, the heat treatment apparatus having a structure in which the heating surface of the hot plate is smaller than the diameter of the wafer. It is.

According to a fourth aspect of the invention, the heat treatment apparatus has a structure in which a cooling means is provided around the outer periphery of the hot plate.

[Effect]

According to the above-mentioned invention as claimed in claim 1, in the insulating film applied to the wafer, the insulating film in the area where the wafer and the hot plate do not contact is compared to the insulating film in the area where the wafer and the hot plate contact. For example, in the development process or etching process for forming an integrated circuit after heat treatment, the film quality becomes unstable.
It becomes possible to remove the resist at the same time.

According to the above-mentioned invention as claimed in claim 2, since the contact state between the outer periphery of the wafer and the hot plate can be brought into a non-contact state, there is no difference in film quality between the insulating film on the outer periphery of the wafer and the insulating film inside the wafer. In addition, it is possible to prevent the insulating film that has spread from the outer periphery of the wafer to the back surface side from adhering to the hot plate.

According to the invention described in claim 4, the difference in film quality between the insulating film on the outer periphery of the wafer and the insulating film inside the wafer can be further increased, so that the insulating film on the outer periphery of the wafer can be removed more easily. It becomes possible.

[Example 1] Fig. 1 is a plan view showing a hot plate and a wafer in a heat treatment apparatus which is an embodiment of the present invention, Fig. 2 is a side view of the hot plate and wafer, and Fig. 3 is a side view of the hot plate and wafer. 1 and 2 are partial sectional views showing cross sections of the hot plate and the outer peripheral portion of the wafer, FIGS. 4(a) and 4(b) are sectional views of essential parts of the wafer explaining the heat treatment method, and FIG. The figure is a sectional view of a main part of a wafer, explaining the steps after heat treatment.

A heat treatment apparatus 1 according to the first embodiment shown in FIGS. 1, 2, and 3 includes a hot plate 4 for baking an insulating film 3 coated on a wafer 2. The heat treatment apparatus 1 shown in FIGS.

The hot plate 4 is made of metal, ceramic, or the like, and is provided with a heat source such as a heater and a temperature detector such as a thermocouple, although not shown.

The shape of the heating surface 4a of the hot plate 4 is, for example, circular, and in the first embodiment, the diameter of the heating surface 4a is smaller than the diameter of the wafer 2. therefore,
In the heat treatment apparatus l of the first embodiment, as shown in FIG. 3, when the wafer 2 is placed on the hot plate 4,
The structure is such that the hot plate 4 does not come into contact with the back surface of the wafer 2 toward the outer peripheral region. That is, even if the insulating film 3 coated on the wafer 2 is made of polyimide and cannot be subjected to edging, the insulating film 3a that wraps around from the outer periphery of the wafer 2 to the back side will not adhere to the hot plate 4.

Further, in the first embodiment, the diameter of the heating surface 4a is set so as to include the chip forming region group 5 formed on the wafer 2. Therefore, the heating surface 4a of the hot plate 4 is in contact with the back surface of the chip forming region group 5 of the wafer 2. That is, the heat treatment apparatus 1 of the first embodiment removes the insulating film 3 on the outer peripheral region of the wafer 2 and the insulating film 3 on the inner region B of the wafer 2 after the heat treatment.
It has a structure that can create a difference in film quality between the two.

Note that the heat treatment apparatus 1 is provided with a positioning mechanism (not shown) for accurately placing the wafer 2 on the hot plate 4. Further, the hot plate 4 is provided with a vacuum suction hole (not shown) for vacuum suctioning the wafer 2.

Next, FIG. 4(a) shows the heat treatment method of Example 1.

This will be explained with reference to (b) and FIG. Note that this Example 1
In the following description, the insulating film 3 is assumed to be made of polyimide, for example.

First, as shown in FIG. 4(a), polyimide is spin-coated onto a wafer 2 by a spinner coating method or the like to form an undried insulating film 3 having a uniform thickness. Note that, unlike positive photoresists, polyimide is coated on the wafer 2 from the front or back side of the wafer 2 after spin coating.
By injecting a solvent into the periphery of the wafer 2, the outer periphery of the wafer 2 and the polyimide that has come around from the outer periphery to the back surface are dissolved.
cannot be removed.

Subsequently, as shown in FIG. 4(b), the wafer 2 is placed on the hot plate 4 of the heat treatment apparatus 1 in an accurately aligned state. Then, the wafer 2 is subjected to a brebake process while being vacuum-adsorbed. At this time, since the heating surface 4a of the hot plate 4 does not come into contact with the back surface of the wafer 2 toward the outer peripheral region, the insulating film 3 toward the outer peripheral region of the wafer 2
There is a difference in film quality between the insulating film 3 in the inner region B of the wafer 2 and the insulating film 3 in the inner region B of the wafer 2. That is, although the solvent evaporates and dries the insulating film 3 in the outer peripheral area A of the wafer 2, its M quality is unstable compared to the film quality of the insulating film 3 in the inner area B of the wafer 2. There is.

Next, after passing through a photolithography process in the chip forming region group 5 (see FIG. 1) of the wafer 2, an etching process is performed. At this time, the insulating film 3 in the outer peripheral region of the wafer 2 whose film quality is unstable is
It can be removed by etching processing without adding a photolithography process to the outer peripheral area A of the wafer 2. That is, in the first embodiment, a photolithography process for removing the insulating film 3 from the outer peripheral region of the wafer 2 is not required.

As described above, according to the first embodiment, it is possible to obtain the following effects.

(1), the diameter of the heating surface 4a of the hot plate 4 is
By making the diameter smaller than the diameter of the wafer 2, it is possible to prevent the insulating film 3a that has come around from the outer periphery of the wafer 2 to the back surface side from adhering to the hot plate 4.

(2) According to (1) above, it is possible to prevent the generation of contaminants caused by the insulating film 3a that has wrapped around the back surface of the wafer 2 and to prevent transport errors of the wafer 2, thereby improving the reliability of the semiconductor integrated circuit device. It becomes possible to improve the yield.

(3) When brebating the insulating film 3 on the wafer 2,
By making the hot plate 4 and the outer peripheral region of the wafer 2 non-contact, and creating a difference in the film quality of the insulating film 3 between the outer peripheral region A of the wafer 2 and the inner region B of the wafer 2, The quality of the insulating film 3 in the outer circumferential region A of the wafer is unstable compared to that of the insulating film 3 in the inner region B of the wafer, so that, for example, a developing process for forming an integrated circuit after heat treatment is required. It becomes possible to remove the resist at the same time in the etching process.

(4) With (3) above, the photolithography process for removing the insulating film 3 from the outer peripheral area of the wafer 2 is no longer necessary, making it possible to reduce the number of manufacturing steps and manufacturing costs of semiconductor integrated circuit devices. Become.

[Embodiment 2] FIG. 6 is a plan view showing a hot plate and a wafer in a heat treatment apparatus according to another embodiment of the present invention, and FIG. 7 is a side view of the hot plate and wafer shown in FIG. 6. , 8th
This figure is a partial sectional view showing the hot plate, the cooling means, and the outer peripheral portion of the wafer shown in FIGS. 6 and 7.

In the heat treatment apparatus 1 of the second embodiment shown in FIGS. 6, 7, and 8, the diameter of the heating surface 4a of the hot plate 4 is smaller than the diameter of the wafer 2, and the heating A water cooling pipe (cooling means) 6 is provided on the outer periphery of the surface 4a. The water cooling pipe 6 is connected to a constant temperature water circulator (not shown).

That is, the heat treatment apparatus 1 of the second embodiment has a structure that allows forcibly cooling the insulating film 3 on the outer peripheral area of the wafer 2 when baking the insulating film 3 applied to the wafer 2. ing. Therefore, the structure is such that the difference between the film quality of the insulating film 3 in the outer peripheral region of the wafer 2 and the film quality of the insulating film 3 in the inner region of the wafer 2 can be made larger than in the case of the first embodiment. ing.

As described above, according to the heat treatment apparatus 1 of the second embodiment, by providing the cooling pipe 6 on the outer periphery of the heating surface 4a of the hot plate 4, the film quality of the insulating film 3 in the outer peripheral area A of the wafer 2 and the wafer Since the difference between the quality of the insulating film 3 and the film quality of the insulating film 3 across the inner region of the wafer 2, that is, the difference in development resistance and etching resistance, can be made larger than in the case of the first embodiment, M3 can be removed more easily than in the first embodiment.

The invention made by the present inventor has been specifically explained based on Examples above, but the present invention is not limited to Examples 1 and 2, and can be modified in various ways without departing from the gist thereof. Needless to say.

For example, in Example 1.2, the case where the shape of the heating surface of the hot plate was circular was explained.
It is not limited to this, and various modifications can be made. For example, the shape may be the same as the chip formation region group 5 formed on the wafer 2, like the heating surface 4b of the hot plate 4 shown in FIG. In this case as well, cooling means may be provided on the outer periphery of the heating surface 4b.

In addition, in the second embodiment, a case was explained in which a cooling means was provided on the outer periphery of the heating surface of the hot plate.
The present invention is not limited to this, and various modifications can be made. For example, a member made of a material having a lower thermal conductivity than the material of the heating surface portion may be provided on the outer periphery of the heating surface.

〔Effect of the invention〕

Among the inventions disclosed in this application, the effects obtained by typical inventions are briefly described below.

(1) 4 That is, when placing a wafer coated with an insulating film on a hot plate and baking the insulating film, the hot plate and at least a part of the outer periphery of the wafer are brought into a non-contact state. According to the invention as set forth in claim 1, a difference is caused in the film quality of the insulating film between a contact area and a non-contact area of the hot plate in the wafer.
In the insulating film applied to the wafer, the film quality of the insulating film in the area where the wafer and the hot plate do not come into contact is unstable compared to the insulating film in the area where the wafer and the hot plate come into contact. For example, in the development process or etching process for forming an integrated circuit after heat treatment, it becomes possible to remove the resist at the same time. As a result, a photolithography process for removing the insulating film on the outer periphery of the wafer becomes unnecessary, and it becomes possible to reduce the number of manufacturing steps and manufacturing cost of the semiconductor integrated circuit device.

(2) According to the invention according to claim 2, which is a heat treatment apparatus having a hot plate for baking an insulating film applied to a wafer, the heating surface of the hot plate is smaller than the wafer. ) In addition to the following effects, it is possible to obtain the following effects.In other words, the contact state between the back surface of the wafer outer periphery and the hot plate can be made non-contact, and the insulation that wraps around from the wafer outer periphery to the back surface side can be made non-contact. It becomes possible to prevent the film from adhering to the hot plate.

As a result, it is possible to prevent the generation of contaminants caused by the insulating film that has wrapped around the back side of the wafer and to prevent wafer transfer errors, thereby improving the reliability and yield of semiconductor integrated circuit devices. -0 (3) According to the invention according to claim 4, wherein a cooling means is provided on the outer periphery of the hot plate, the difference in film quality between the insulating film on the outer periphery of the wafer and the insulating film inside the wafer can be further increased. Therefore, it becomes possible to more easily remove the insulating film on the outer periphery of the wafer.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a hot plate and a wafer in a heat treatment apparatus that is an embodiment of the present invention, FIG. 2 is a side view of the hot plate and wafer, and FIG. 4(a) and 4(b) are sectional views of essential parts of the wafer to explain the heat treatment method. FIG. 5 is a partial sectional view showing the cross section of the outer circumferential portion of the hot plate and wafer shown in the figure. FIG. 6 is a plan view showing a hot plate and a wafer in a heat treatment apparatus according to another embodiment of the present invention; FIG. A side view of the plate and wafer, FIG. 8 shows the hot plate shown in FIGS. 6 and 7,
FIG. 9 is a partial cross-sectional view showing a cross section of the cooling means and the outer circumferential portion of the wafer. FIG. 9 is a plan view showing the heating surface of the hot plate and the wafer in a heat treatment apparatus according to another embodiment of the present invention. l...heat treatment equipment, 2...wafer 3゜3a...
・Insulating film, 4... Hot plate, 4a, 4b...
heating surface, 5... chip forming region group, 6... cooling pipe,
A: outer peripheral area, B: inner area. Figure: Heat treatment device Figure (b) Figure 3 Figure (a) Figure 6: Cooling means Figure 7

Claims (1)

[Claims] 1. When placing a semiconductor wafer coated with an insulating film on a hot plate and baking the insulating film, the hot plate and at least a part of the outer periphery of the semiconductor wafer are not in contact with each other. A heat treatment method characterized in that the semiconductor wafer is made to have a different quality of an insulating film between a contact area and a non-contact area of a hot plate in the semiconductor wafer. 2. A heat treatment apparatus having a hot plate for baking an insulating film coated on a semiconductor wafer, characterized in that the heating surface of the hot plate is made smaller than the diameter of the semiconductor wafer. 3. The heat processing apparatus according to claim 2, wherein the shape of the heating surface of the hot plate is the same as the shape of a group of chip forming regions formed on the semiconductor wafer. 4. The heat treatment apparatus according to claim 2 or 3, further comprising a cooling means provided on the outer periphery of the heating surface of the hot plate. 5. The heat treatment apparatus according to claim 2 or 3, characterized in that a member made of a material having a lower thermal conductivity than the material constituting the heating surface is provided on the outer periphery of the heating surface of the hot plate.