JPS6113373B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor manufacturing apparatus for simply and reliably heat treating a semiconductor substrate (wafer).

Many of the manufacturing processes of semiconductor devices require a photoetching process. In general, the photoetching process follows the steps of photoresist application, first baking, exposure for patterning, development, second baking, and etching. The first baking before development is a drying process necessary to evaporate the solvent in the photoresist and improve adhesion to the wafer.
Heating is carried out at ~150°C for about 5 minutes to 1 hour. The second baking after development is a process of selectively peeling off and baking the remaining resist film. The purpose of these first and second baking steps is to sufficiently dry the resist film, increase the adhesion strength to the wafer, and perform accurate patterning. This is an extremely difficult task in today's semiconductor device manufacturing process, where finer patterns are formed.

The following three methods are generally used for baking such wafers. The first method is called the oven method, in which a heat source is placed on the inside surface of a sealed box, and the internal atmosphere is heated to bake the semiconductor substrates housed in the box. In this case, a plurality of semiconductor substrates (wafers) are set on a wafer tray or the like, and the wafer tray is taken in and out of the sealed box (furnace), so handling of the wafers is easy and work efficiency is high. However, since the above-mentioned wafer tray has a structure in which wafers are set in a line,
Thermal histories of wafers at the edges of the tray and wafers at the center of the tray differ. FIG. 1 shows the change in temperature at the end of the tray (× in the figure) and temperature at the center of the tray (○· in the figure) with time (min) plotted on the horizontal axis. As is clear from this, after being inserted into the furnace (0 minutes), the temperature at the edge of the tray rises rapidly due to the heat source on the inner surface, and after being removed from the furnace (after 14 minutes), the temperature at the center of the tray increases rapidly. The temperature of a semiconductor wafer does not drop easily because of the heat from other wafers arranged in front and behind it. In this way, in the above-mentioned oven baking method, which is the most convenient and widely used method for handling wafers, heating control (thermal history) differs from wafer to wafer, so even if the absolute value of temperature is controlled reliably, This method has the disadvantage that it cannot improve the yield of semiconductor devices that require fine patterning. The second baking method is an infrared radiation method. This has the disadvantage that it is difficult to accurately adjust the temperature of the wafer itself because the wafer is heated by radiant heat. A third baking method uses, for example, a hot plate with a built-in heater inside the plate. In this method, a plurality of wafers are placed on a single hot plate at the same time, and the heat from the hot plate is directly applied to each wafer for baking. This method allows baking by controlling the temperature of the wafer itself with high accuracy because the surface temperature of the hot plate can be easily controlled, but the wafers must be taken out from the wafer carrier and handled separately one by one. This has been an obstacle to automating the semiconductor manufacturing process, and it has been difficult to efficiently increase the yield of products.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to eliminate the drawbacks of the above-mentioned hot plate method in handling wafers, and to provide a semiconductor manufacturing apparatus that can perform baking with high precision and efficiency.

Hereinafter, embodiments of the present invention will be sequentially described with reference to the drawings. In the first embodiment shown in FIGS. 2a to 2c, the wafer tray shown in FIG. 2a and the heating tray shown in front and side views in FIGS. The semiconductor substrates are formed at corresponding positions (intervals) so that a plurality of semiconductor substrates can be transferred at once. Wafer tray 1 in Figure 2 a
is a box in which a plurality of grooves 2 ₁ , 2 _{2 .} . . are formed so that a plurality of semiconductor substrates (wafers) can be held at a distance from each other. In addition to the wafer insertion opening 3, windows are formed on all the remaining five sides of the box to allow the wafer to be moved between the boxes and to improve ventilation. In the semiconductor manufacturing process, this wafer tray 1 normally stores 20 to 30 wafers and converts them into cassettes into one unit.The wafer tray 1 is used for the photoetching process described above while reorganizing the lot for each process. pass through.

The heating tray 4 shown in FIGS. 2b and 2c has an envelope made of a material with high thermal conductivity, and the inside thereof is made up of a plurality of heating plates 4 ₁ , 4 ₂ . . . in which heaters are embedded, for example. Separated. These hot plates 4 ₁ , 4 ₂ ...
The distance between each hot plate 4 is the same as that of the wafers (not shown) held on the wafer tray 1.
₁ , ₄₂ ... form openings ₅₁ , ₅₂ ... for wafer insertion and ejection.

The heating tray 4 has a built-in heater mechanism also in the back surface 6 facing the openings 5 ₁ , 5 ₂ . . . , so that the overall temperature of the heating tray 4 can be adjusted. There is. Note 7
shows a wafer inserted through the opening ₅₁ .

In this way, the opening 5 is made equal to the wafer holding interval of the wafer tray 1 used as a carrier.
It is possible to transfer all the wafers from the carrier to the heating tray 4 formed with ₁ , 5, ₂ , etc. at once, compared to the conventional method of transferring wafers one by one onto the hot plate. It saves a lot of time and effort.

When transferring the wafer tray 1 to the heating tray 4, for example, the wafer tray 1 is joined to the openings 5 ₁ , 5 ₂ . . . of the heating tray 4, and then the openings 5 ₁ , 5 ₂ . When the wafer is tilted to face the heating tray 4, the wafer slides and fits into the heating tray 4 due to its own weight.

After the heating process is completed, the wafer tray 1 is similarly bonded to the openings 5 ₁ , 5 ₂ . . . of the heating tray 4, tilted in the opposite direction, and all wafers are transferred to the wafer tray 1 at once. be able to. Note that it is desirable that the number of openings 5 ₁ , 5 ₂ . . . be equal to or greater than the number of wafers that can be stored in the wafer tray 1 used.
The openings 5 ₁ , 5 ₂ . . . are the heating trays 4
If a pair of openings are formed not only on one side but also on two opposing sides, they can be used separately as an insertion opening and an ejection opening, and in this case, these openings can be selectively opened and closed. Form the lid body (stopper) etc.

According to the configuration of this embodiment, a plurality of wafers can be heat-treated easily and reliably, and work efficiency can also be improved. The heating tray 4 used as a heating mechanism is configured so that heat is directly conducted from the heating plates 4 ₁ , 4 _{2 .} . . on which the wafers are placed, similar to the above-mentioned hot plate method, so temperature control is ensured. Not only can the temperature of all stored wafers be set equally, but the thermal history can be easily adjusted. Therefore, the resist film baking process in the photoetching process can be carried out reliably, and the manufacturing yield of semiconductor devices can be increased.

FIG. 3 is a perspective view showing a second embodiment of the invention, in which the wafers 11 ₁ and 11 are connected to the heating mechanism 10.
_2. It is devised so that the insertion and ejection of... are performed automatically in sequence. That is, the heating mechanism 10 includes a plurality of hot plates 12 ₁ , 1 each having a built-in heater.
_{2 2 . _ _}
It is removably fixed on the top of the heating mechanism 10 and can be moved up and down in front of the heating mechanism 10 by rotation of the rotating shaft ₁₄₁ . As shown in the figure, in the wafer carrier 13, the wafers _{11 3} , 11 ₄ . . . are held closer than the spacing between the hot plates _{12 1 ,} 12 _{2 .}
The carrier 13 movement control mechanism sequentially aligns the wafer holding portion of the carrier 13 with the hot plate surface, and then moves the insertion plate 15, which inserts the wafer ₁₁₃ onto the hot plate ₁₂₃ , into the heating mechanism 1.
By moving the wafer 113 toward the front of the wafer 113, the wafer ₁₁₃ can be stored. Further, the discharge plate 16 on the back side of the heating mechanism 10 similarly moves up and down together with the movement control mechanism, and sequentially discharges the stored wafers 11 ₁ , 11 ₂ . . . after the heating process is completed, and transfers them to the wafer carrier. It is designed to return to within 13.

In contrast to the first embodiment, in which all the wafers can be stored in the heating mechanism and discharged at the same time, this second embodiment allows the wafers set in the carrier to be stored or discharged one after another. Therefore, in order to ensure that all wafers are heat-treated with the same thermal history, it is necessary to discharge the wafers in the opposite order to the order in which they were stored. The feature of this embodiment is that, as mentioned above, by automating the heat treatment process, the manufacturing process of semiconductor devices can be simplified, semiconductor elements can be provided efficiently and at low cost, and there is no restriction on the spacing between each hot plate. Therefore, the heat capacity of the hot plate can be sufficiently increased, and the temperature of the wafer can be controlled more reliably.

In the first and second embodiments described above, the temperature control of the wafers to be heat-treated is such that when the set temperature is 80°C, the temperature distribution among multiple wafers that are processed simultaneously is within ±3°C, and the same heating plate is used. The temperature distribution for the wafers processed above is within ±1° C. and is extremely accurate. Similarly, in each of the above embodiments, when the set temperature is 150°C, the temperature distribution between wafers is within ±4°C, and the temperature distribution by the same hot plate is within ±1.3°C, which is different from that of the conventional hot plate. This shows that heat treatment can be performed without sacrificing the advantage of this method, that is, the ease of temperature control.

Therefore, the adhesion of the photosensitive agent applied to the wafer is improved, and lateral erosion during etching can be suppressed to 0.5 μ or less. Furthermore,
In the conventional infrared irradiation method, the number of pinholes per unit area (cm ² ) of the wafer surface is reduced by heat treatment.
The temperature was about 0.5, but because the temperature setting is performed reliably, the device of this invention has a temperature of 0.05/ ^cm2 , which is about 1/10.
Pinholes are reduced below. Thus, according to the present invention, it is possible to provide a semiconductor manufacturing apparatus that takes advantage of all the advantages of the conventional hot plate method, increases the efficiency of heat treatment, and contributes to improving the manufacturing yield of semiconductor elements.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing changes in wafer temperature using the conventional oven method, FIGS. 2 a to c are diagrams showing a first embodiment of the semiconductor manufacturing apparatus of the present invention, and FIG. It is a figure showing an example. 1... Wafer tray (carrier), 4... Heating tray (heating mechanism), 10... Heating mechanism, 1
3...Wafer carrier.

Claims (1)

[Scope of Claims] 1. A shelf-shaped heating mechanism comprising a plurality of temperature-adjustable heating plates and having an opening as an insertion/ejection port for a semiconductor substrate (wafer) between the heating plates; A semiconductor manufacturing apparatus comprising a wafer carrier which can be handled separately and holds a plurality of wafers at intervals corresponding to the ejection openings. 2. A shelf-shaped heating mechanism that is equipped with a plurality of temperature-adjustable heating plates and has an opening for inserting and discharging semiconductor substrates (wafers) between these heating plates, and that can be handled separately from this heating mechanism. A wafer carrier that holds a plurality of wafers, a movement control mechanism that attaches the wafer carrier and moves it along the opening, and the movement control mechanism causes the wafer holding part of the wafer carrier to move along the opening. 1. A semiconductor manufacturing apparatus comprising means for sequentially inserting or ejecting wafers between a wafer carrier and a heating mechanism when the wafer carrier faces the heating mechanism.