JPH01738A - Heat treatment method for semiconductor wafers - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for heat treatment of semiconductor wafers.

[Prior Art] Etching is one of the manufacturing processes for semiconductor devices, and in order to perform this etching, it is necessary to form a photoresist film on the surface of a semiconductor wafer, such as a silicon wafer, and then photoprocess this. In forming this photoresist film, after coating the wafer with a photoresist liquefied using a solvent as a photoresist film, the photoresist is coated on the wafer in order to improve the photosensitivity, phenomenon processing characteristics, or etching processing characteristics of this film. The photoresist film is heat-treated to perform so-called modification. This modification also includes removing solvents, strengthening adhesion, and improving etching resistance.

Heat treatment equipment such as infrared baking equipment, hot air circulation baking equipment, dielectric heating baking equipment, etc., and vacuum baking equipment are used as means for performing this type of reforming, but the former is preferred in terms of productivity and automation. is advantageous.

[Problems to be Solved by the Invention] In conventional heat treatment, the beta effect is performed with the photoresist film exposed in the processing equipment, so foreign matter (dust, etc.) present in the equipment may adhere to the photoresist film. It has the disadvantage of being easy. If such foreign matter adheres to the photoresist film, the light will be blocked by the foreign matter during the exposure process, and the photoresist film under the foreign matter will not be exposed. As a result, a desired semiconductor element pattern cannot be obtained on the wafer, and in particular, if foreign matter adheres to the wiring portion, the wafer may be cut.

Therefore, in the past, it was considered essential to conduct a visual inspection after the heat treatment process of the photoresist film, and in fact, defective products were discovered during this inspection, lowering the product yield, and causing problems in the manufacturing process. This has become an obstacle to reducing man-hours.

For this reason, the present inventors investigated the cause of the generation (adhesion) of foreign matter and found that foreign matter was generated from the driving part for transporting the object on which the coating was formed inside the heat treatment equipment, and that objects were not allowed to enter the equipment from outside the equipment. It was found that most of the foreign matter was contained in the outside air that entered during transport.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a heat treatment that can prevent foreign matter from adhering to a photoresist film formed on a semiconductor wafer and can provide a high yield.

[Means for Solving the Problems] Based on the results of this investigation, the present invention is configured to expel foreign matter from the driving unit to the outside of the processing chamber and to prevent outside air from entering the processing chamber.

[Embodiment] Figures 1 and 2 show a front sectional view and a side sectional view of an infrared baking device applied to the method of the present invention.

In the figure, reference numeral 1 denotes the main body of the apparatus, inside which a partition wall 2 is erected at a position closer to the rear side to define a circulation chamber 3 on the rear side, which includes an inert gas source (not shown). A gas supply pipe 4 connected to the gas supply pipe 4 is open and continuous. On the front side of the partition wall 2, mesh plates 5 and 6 are arranged on the upper and lower sides, respectively, and from the top, there are a ventilation chamber 7, a beta chamber (processing chamber) 8. An exhaust chamber 9 is defined.

In addition, through holes 10 and 11 are formed in the upper and lower parts of the partition wall 2, and an air supply fan 12. An exhaust fan 13 is installed inside, and as shown in the arrow, the circulation chamber 3→ventilation chamber 7→bake chamber 8→
The gas is circulated along the route from the exhaust chamber 9 to the circulation chamber 3. A pre-filter 14 is disposed at a portion of the through hole 10 that communicates the circulation chamber 8 and the ventilation chamber 7, and a main filter 15 is disposed between the ventilation chamber 7 and the bake chamber 8.

On the other hand, in the lower part of the baking chamber 8, a conveying means 16 having a belt conveyor as a driving unit is disposed extending along both sides, and conveys the wafer 17 from left to right in FIG. A loader section 18 is provided on the left and right sides of the main body 1. The unloader section 19 is arranged, and the wafers 17 in the loader section 18 are transferred to the transfer means 16 through the carry-in port 20 of the main body side wall 1a, and the wafers 17 on the transfer means 16 are transferred to the unloader section through the carry-out port 21 of the main body side pla. Transfer. Furthermore, three infrared lamps 22 are installed in the upper part of the baking chamber 8 to connect the conveying means 16.
A number 4 is provided in parallel with the wafer, and the wafer transported by the transport means 16 can be heated. 28 is a reflecting plate.

[Effects of the Invention] According to the above configuration, the inert gas supplied from the gas supply pipe 4 into the circulation chamber 8 enters the ventilation chamber 7 through the pre-filter 14, and is further purified through the main filter 15 and baked. The current flows into chamber 8. In the beta chamber 8, the gas flow is directed downward by the action of the mesh plate 5, resulting in a so-called downflow. Here, the foreign matter generated by the driving part of the conveyance means 16 is carried by the flow and moved downward, passed through the mesh plate 6 to the exhaust chamber 9, and then passed back to the circulation chamber 3. This gas will be circulated again through the same route as above,
Prefilter 14. They are each cleaned by the main filter 15 and flowed into the baking chamber 8 to remove foreign matter in the baking chamber 8.

On the other hand, the wafer 17 is supplied into the bake chamber 8 from the loader section 18 through the loading port 2o, and is heated (baked) by the radiant heat of the infrared lamp 22 and the heat of the heated gas in the bake chamber while being transferred by the transfer means 16. After the heat treatment, it is carried out from the carrying out port 22 to the unloader section 19. and,
At this time, by adjusting the flow rate of the gas to maintain a positive pressure (relative to the outside air) inside the bake chamber 8, even when loading and unloading wafers, outside air enters the bake chamber 8 through the loading port 20 and the loading port 21. Therefore, no foreign matter contained in the outside air can enter. The pressure inside the baking chamber 8 can be adjusted by adjusting the flow rate of the gas supplied from the gas supply pipe 4, the rotational speed of the air supply fan 12, and the like.

As a result of the above, foreign matter generated from the drive unit of the transport means is removed in the bake chamber 8, and foreign matter contained in the outside air is prevented from entering together with the outside air, so that the foreign matter is not exposed to the photoresist film formed on the surface of the wafer 17. It is possible to prevent adhesion and improve product yield.

[Modifications] Figs. 3 to 5 show other different embodiments of heating devices applicable to the present invention. In these figures, the same parts as those in the embodiment described above are designated by the same reference numerals, and the explanation thereof will be omitted.

Figure 3 shows the configuration as a hot air circulation system.

In place of the infrared lamps 22 in the previous example, heaters 24 are disposed on both side walls of the circulation chamber 8 to heat the gas as it flows through the circulation chamber 8 and ventilate it into the baking chamber 8.

The wafer 17 is heated.

The gas supply pipe 4 is connected to the lower part of the circulation chamber 3.

Figure 4 shows a 4+3 plate heating system, in which a heater 25 is installed inside the belt conveyor serving as the conveying means 16.
The wafer is heated from a close distance while the wafer is transported on top of the wafer.

FIG. 5 shows a dielectric heating (microwave heating) system configuration in which a magnetron 26 is placed in the ventilation chamber 7 and microwaves are radiated into the baking chamber 8 to dielectrically heat the wafer 17. .

As mentioned above, each example has a different heating method, but it is the same as the previous example in that the inert gas is thrown down into the baking chamber and the inside pressure is positive, and the adhesion of foreign matter is prevented as in the previous example. It goes without saying that it can be done.

Here, the heating device applied to the present invention can be applied to other devices as long as it has a processing space and requires cleanliness between processing chambers, such as a photoresist pre-bake furnace, It can be applied to photoresist post-bake ovens, automatic coating and baking equipment, and automatic developing and baking equipment.

As described above, according to the present invention, the gas is caused to flow down into the processing chamber, and the pressure inside the processing chamber is particularly positive, so that foreign matter generated from the drive unit inside the processing chamber or foreign matter contained in the outside air is removed from the processing chamber. It is possible to prevent the product from adhering to the product and improve the yield of the product.

[Brief explanation of the drawing]

FIGS. 1 and 2 are front sectional views of one embodiment of a heating device applied to the method of the present invention, and FIGS. 3 to 5 are examples of other different heating devices applied to the present invention. FIG. 1... Apparatus main body, 3... Circulation chamber, 5, 6... Mesh plate, 7... Ventilation room, 8... Processing chamber (bake room), 9... Exhaust chamber, 12 ...Air fan, 13
...Exhaust fan, 14...Pre-filter, 15...
- Main filter, 16... Transfer means, 17... Wafer, 18... Loader section, 19... Unloader section, 22... Infrared lamp, 24... Heater, 25...
... Heater, 26... Magnetron. Figure 1 Figure 2 Figure 4 Figure 5

Claims (1)

[Claims] 1. A semiconductor wafer characterized by comprising the steps of applying photoresist on one main surface of the semiconductor wafer, and transporting the semiconductor wafer into a heat treatment chamber through which a clean gas can flow in a downflow state, and heating the semiconductor wafer. Heat treatment method.