JPS6120043A - Detection of end point of development - Google Patents

Abstract

PURPOSE:To eliminate the unstableness and non-efficiency in the detection of the end point of photoresist development by connecting a connecting means consisting of a metallic material to a metallic film through the resist of an exposed substrate to make one electrode, using a material consisting of a metallic material different from said metallic material as the other electrode and dipping said material into a developing soln. CONSTITUTION:The developing soln. 2 consisting essentially of, for example, sodium hydroxide, is incorporated in a vessel 1 and the substrate 3 consisting of, for example, silicon, disposed with, for example, an aluminum layer 21 deposited by evaporation and a photoresist (photoresist 23 and unexposed photoresist 22) completed of an exposing stage on the aluminum layer and a platinum wire 4 are dipped in the soln. 2. The aluminum wire provided with a holder 5 at the top end is brought into contact with the aluminum layer on the substrate 3 by breaking through the resist film to make one electrode and the wire 4 is used as the other electrode in order to monitor the progressing condition of the development by the soln. 2 in the exposed part 23 on the substrate 3. Lead wires 7a and 7b are connected to the respective top ends of the aluminum wire 6 and the platinum wire 4 and are connected to an amplifier 9.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for detecting the end point of development, and more particularly to a method for reliably detecting the end point of photoresist development in a photoprocess used in the manufacture of semiconductor devices. be.

Conventional photoprocessing involves the first process of transferring a mask pattern onto a photoresist, and the second process of removing the resist by etching the underlying W'fr using the resist pattern.
It is broadly divided into the process of

The above process II includes the steps of resist coating, exposure, development, and post baking. Photoresist used in the resist coating process) f1As is well known, there are negative and positive types.For example, in a positive type photoresist, the light-irradiated area is soluble in an alkaline developer, and the unexposed area is insoluble, so the solubility A pattern is formed by utilizing the points that cause the difference between the two.0 In the developing process, a special solution for cloth plates is used in both negative and positive types. As described above, development of a resist pattern is carried out by utilizing the difference in solubility between the foggy light area and the unexposed area, and visual inspection is currently the most reliable method for inspecting the end point of development. There are two methods of development: immersion and spraying.
Particularly in the former case, it is difficult to control the temperature, concentration, change over time, etc. of the developer, and inspection of the end point of development is often done visually and by trial and error. Since the photoresist is colorless and bright, it is extremely difficult to determine the end point of development, and this problem is overcome by overdevelopment. However, in recent years, with the miniaturization of resist patterns, overdevelopment due to mere visual inspection has become a problem.

Problems to be Solved by the Invention The present invention attempts to solve the above-mentioned instability and inefficiency of end point inspection of photoresist development.

An object of the present invention is to provide a quantitative development end point detection method that does not depend on human senses. .

Another object of the present invention is to provide a method for detecting the end point of development which enables all development to be carried out at the same level at all times.

Still another object of the present invention is to provide a method for detecting the development end point that can be fully automated.

Means for Solving the Problem The above problem involves forming a resist layer on a metal film formed on a substrate, exposing the resist layer to form a desired pattern, and then exposing the exposed substrate to light. According to the present invention, in the development deviation point detection method, the connecting means made of a metal material is entirely connected to the metal film through the resist of the exposed substrate to form one electrode, and an object made of a metal material different from the metal material. is immersed in the developer as the other electrode, and the flow between the two electrodes is monitored. This problem is solved by the characteristic method of detecting the end point of development.

According to the present invention, it is connected to the metal film through the resist,
The current flowing between the connection means which becomes one electrode and the other electrode is 0 at the start of resist development, but gradually increases as resist development progresses, and the current change becomes maximum at 1. When this occurs, it can be considered that the entire development (main development) is completed. Alternatively, development may end when the level reaches a certain value, or development may end when the level reaches a peak.

Example Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a schematic diagram showing an embodiment for explaining the present invention in detail. FIGS. 2A and 2B are schematic cross-sectional views showing the resist development process.

In FIG. 1, a developer 2 containing, for example, sodium hydroxide as a main component is stored in a container 1, and within the developer 2, a vaporized aluminum layer (2A, 2B 21) in the figure and g on the aluminum layer.
The positive photoresist that has undergone the x-x process (the small photoresist 23 and the photoresist 22 exposed to light in FIG. 2A VC), the substrate 3 made of, for example, silicon, and the platinum wire 4 are immersed.

In order to monitor the development progress 1ii1 in the developing solution 2 of the photosensitive area (FIG. 2A, 23) on the substrate 3, it is held at the tip 45.
The aluminum layer on the aluminum substrate 3 provided in
Platinum wire 4t - the other electrode.

The tip of the holder 5 is made of photoresist (not easily broken).
A core electrode connector that can be added with a high capacity is preferred. The upper ends of each of the aluminum wire 6 and the platinum wire 4 (
' Lead wires 7 a and 7 b are connected to the amplifier 9 . Further, lead wires 7a and 7bi- are connected through a resistor 8.

Figure 1: Sea urchin substrate 3, aluminum wire 6, and platinum wire 4
? Current Ig! When immersed in the liquid 2, the 4 platinum wire + electrodes and the aluminum wire 61jI-
Current flows as one pole.

The material connected to the metal film on the substrate 3 is preferably the same type of material as the metal film provided on the substrate in order to improve detection accuracy. This is because the combination of the four conductive layers and the different materials and the material in contact with the substrate 3 are both immersed in the developer, forming a short circuit for the battery.
This is because correct monitoring of the home becomes impossible. Metallic materials may be used as long as the connecting material is sealed with, for example, fluororubber so that it does not come into contact with the developer.

When the three substrates are immersed in the developer plate 1 and the start switch is pressed, a timer operates and interrupts the time side 611J to the processing device 11 equipped with an arithmetic system fI41 and a storage every second, for example. The contact 15 of the relay is closed for about 20 milliseconds to measure the current flowing through the processing device 11.
It is input to the processing device 11 via the AD converter 101 and compared with the value of the developing current 1 storage circuit 12. Processing device 1
When the difference between the current III current input to 1 and the developing current value of the memory circuit 12 is small, the newly measured electric current,
The value is stored in the developing current storage circuit 12.

The newly measured current value is the same as the previously measured 11! When the current value, ie, the voltage E3, significantly increases from the value in the developing current storage circuit 12, it is determined that the end point of Vr main development has been reached (point A in FIG. 3). Further, the development can be completed as the peak voltage E4 - the passed point B1 - the end point of additional development. The additional development factor is stored in the additional development factor storage circuit 13 for a predetermined period of time from the end of main development as in the above example.
It is clear that the present invention can also be realized by performing additional development with the time point at which all peaks are detected as the end point of main development. . In the figure, 14 is a mechanism such as a buzzer or a timer that notifies the completion of development.

In this embodiment, the electrode facing the substrate 3 is a platinum wire. Any conductive material that is different from the metal used under the resist layer can be used, and it is of course possible to use other metals other than aluminum, such as molybdenum, tungsten, or chromium, as the metal film under the resist layer.

FIG. 4 is a schematic diagram showing one embodiment of a developing container for carrying out the method of the present invention.

If constructed as shown in FIG. 4, the developer container consists of an outer tank 30 and an inner tank 31. The inner tank 31 is filled with a developer 2, and a plurality of wafers are transported into the developer 2 by a carrier 32. 33
(on which a conductive layer and a resist layer are formed) is immersed. The carrier 32 is connected to a motor 35 via a transport mechanism 34, and is swung up and down to increase the developing efficiency and improve the uniformity on the wafer. Connect the aluminum wire to the aluminum metal film of the wafer on one of the multiple wafers 33 (9).
^1- It is connected in this way. Further, a platinum wire 4 serving as one electrode is immersed in the developer 2 in the same manner as shown in FIG. 1, and the aluminum wire and platinum wire are connected to a detection device. The developer 2a overflows from the upper part of the inner tank 31, is sucked up by the pump 36, and is again supplied into the inner tank 31 from the lower part.
8 is stirred to improve the development efficiency and the uniformity of the wafer development (8).

As described in detail, since the method of the present invention detects the development state electrochemically, it is possible to improve reproducibility and efficiently automate the optimum development process. Furthermore, the present invention enables frequency control of crystal oscillators, surface acoustic wave filters, etc.

That is, since the end point is detected electrochemically without visual inspection, the reproducibility is improved, and the subsequent etching can be performed with high precision, making it possible to reduce the overall variation in heating frequency.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing one embodiment for explaining the present invention in detail, FIGS. 2A and 2B are schematic cross-sectional views showing the resist developing process chamber, and FIG. FIG. 4 is a graph showing the relationship between developing voltage, and FIG. 4 is a schematic diagram showing one embodiment of a developing container for carrying out the entire method of the present invention. ]... Container, 2... Developer, 3...
... Substrate, 4... Platinum wire, 5... Holder,
6... Aluminum wire, 7m, 7b...
・Lead wire, 8... Resistor, 9... Amplifier, 10... AD converter, 11...
・Processing device with arithmetic control function, 12... Development current storage circuit, 13... Additional development 7 actor storage circuit, 14... Buzzer or timer, 1
5...Reed relay contact, 16...Start switch, 21...Aluminum layer, 22...
...Negative resist, 23...Negative resist) (1
1 optical part), 30...Outer tank, 31...Inner tank, 32...Carrier, 33...Wafer, 34...Transportation Mechanism, 35...Motor, 36...Pump. 1) Yamagaruki-ta□

Claims (1)

[Claims] 1. Forming a resist layer on a metal film formed on a substrate, exposing the resist layer to form a desired pattern, and then detecting the end point of development of the exposed substrate. In the method; a connecting means made of a metal material is connected to the metal film through the resist of the exposed substrate to serve as one electrode, and an object made of a metal material different from the metal material is immersed in a developer as the other electrode. . A method for detecting the end point of development, comprising monitoring a current flowing between the two electrodes. 2. The method according to claim 1, wherein the metal material is made of the same material as the metal film. 3. A method according to claim 1, characterized in that the connecting means is coated so as not to come into contact with the developer during immersion in the developer. 4. A change in the current flowing between the two electrodes is detected and determined as the end point of the main development, and further development is performed based on an additional development factor, and the end point of the additional development is determined as the end point of the development. A method according to claim 1. 5. The method according to claim 4, wherein the change in the current is a peak value. 6. The method according to claim 4, wherein the change in current is at a maximum slope point. 7. The method according to claim 1, wherein the current is monitored using means comprising a development state monitoring means, an additional development factor storage means, and an arithmetic control means.