JPS61167947A - Method for detecting end point of development - Google Patents

Abstract

PURPOSE:To facilitate detection of the end point of development by connecting the first conductor to a conductive layer through the resist of a substrate as one electrode, immersing the second conductor in a developing soln. as the other electrode, applying voltage between both electrodes, and watching the current. CONSTITUTION:The substrate 3, the conductor with 6, and the platinum wire 4 are immersed in the developing soln., and when voltage is applied from an electric cell 15 between the wire 4 as the positive electrode and the wire 6 as the negative electrode, current flows. The material of the conductor 6 to be connected with the conductive layer of the substrate 3 is made of a material same in kind as the material of the conductive layer in order to enhance detection accuracy. When the substrate 3 is immersed in the developing both and a starting switch is pushed, a timer is actuated to count time, and, e.g., at each second, a processing device 11 provided with a computer controller is interrupted and allowed to close the cell 15 for about 20mmsec and to measure the developing current. When the measured current increase rate drops remarkably compare with the value of a developing memory circuit 12, it is judged to reach the end point, thus permitting efficient optimum development and its automation to be attained.

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 resist development used in the manufacture of semiconductor devices.

Problems to be Solved by the Prior Art and the Invention The development of resist patterns used in the manufacture of semiconductor devices is carried out by utilizing the difference in solubility between exposed areas and unexposed areas. At this time, the end point of development of the resist pattern is mainly determined by visual inspection.

In such visual inspection, as the resist pattern becomes finer, a reliable end point of development cannot be obtained.

Therefore, the present inventors filed an application regarding a method for detecting the end point of electrical photoresist development (Japanese Patent Application No. 59-14-0551).
issue). However, in photoprocessing in the manufacturing method of semiconductor devices, the line width of photoresist patterns is limited to 1 to 2 μm, and in the future, line widths of submicron patterns will be required.
For 56-bit memory and IM or 4M bit memory, a process using electron beam lithography or the like was required, although photoprocessing could not be used. However, in the case of a positive electron beam resist with good resolution, the developer used is an organic solvent containing isopropyl alcohol or the like as a main component, and in the method according to the application method, the electromotive force was so small that it was difficult to detect the end point.

Means for Solving the Problems According to the present invention, the above problems are solved by forming a resist layer on a conductor layer formed on a substrate, and exposing the resist layer to light or X-rays to form a desired pattern. In the method for detecting the end point of development of the exposed substrate after the exposed substrate is exposed to light or X-rays or exposed to electron beam, a connection made of a first conductive material is made to the conductive layer through the resist of the substrate exposed to light or X-rays or exposed to electron beam. Connecting the means to form one electrode, immersing an object made of a second conductive material in a developer to form the other electrode, applying a voltage between the two electrodes, and monitoring the current flowing between the two electrodes. This problem is solved by a method for detecting the end point of development, which is characterized by the following.

According to the present invention, the conductor layer is connected to the conductor layer through the resist,
The current flowing between the connecting means serving as one electrode and the other electrode is VQ when the conductive layer is completely covered with non-conductive resist at the start of resist development, but as the resist development progresses and the conductive layer The current gradually increases as the exposure progresses, and the time when the current change reaches its maximum can be regarded as the end of development (main development). Alternatively, development may end when the level reaches a certain value, or 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 one 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 whose main component is, for example, isopropyl alcohol is stored in a container 1, and within the developer 2 is a vapor-deposited chromium layer (see FIGS. 2A and 2B) with a thickness of 3,000 to 1 μm, for example. 21) and the ≠-→ for example, polymethyl methacrylate which has undergone an electron beam drawing process on the chromium layer.
) (PMMA) for electron beams (the positive resist 23 drawn in FIG. 2A, the undrawn positive resist 22), a substrate 3 made of, for example, glass and a platinum wire 4 are immersed. There is.

Developer 2 in the electron beam drawing section (FIG. 2A, 23) on the substrate 3
In order to monitor the progress of development, a Teflon coated conductive wire with a holder 5 at its tip was brought into contact with the chromium layer on the substrate 3 through the resist film as one electrode, and the platinum wire 4 was used as the other electrode. Use as an electrode.

The tip of the holder 5 is preferably an electrode connector capable of applying a force capable of easily breaking the positive resist. Vinyl lead wires 7a and 7b are connected to the upper ends of the conducting wire 6 and the platinum wire 4, respectively, and lead to an amplifier 9. Furthermore, vinyl lead wires 7a and 7b are connected via a resistor 8.

As shown in Figure 1, the substrate 3, conductive wire 6, and platinum wire 4 are
When the battery 15 is immersed in the battery and the battery 15 is applied, a current flows with the platinum wire 4 as an electrode and the conducting wire 6 as one pole.

The conductive material connected to the conductor layer on the substrate 3 is preferably the same type of material as the conductor layer provided on the substrate in order to improve detection accuracy. This is because when the conductive material is of a different type from the conductor layer, the materials in contact with the substrate 3 are both immersed in an organic solvent developer, and a short circuit is formed there due to ionization, causing the development to fail. This is because proper monitoring will be disrupted. A different type of conductive material may be used as long as the connecting material is sealed with fluororubber such as Shpon Co., Ltd., such as fluoro rubber so as not to come into contact with the developer.

When the substrate 3 is immersed in the developing tank 1 and a start switch is pressed, a timer is activated to measure time, and interrupts the processing device 11 equipped with an arithmetic control function every second, for example. The processing device 11 closes the battery 15 for about 20 milliseconds and measures the developing current. The current due to development is converted to voltage by resistor 6,
The signal is amplified by the amplifier 9, inputted to the processing device 11 via the AD converter 10, and compared with the value in the developing current storage circuit 12. When the rate of increase in the developing current input to the processing device 11 tends to increase, a newly measured current value is stored in the developing current storage circuit 12.

The end point of main development was reached when the newly measured current increase rate became significantly lower than the previously measured current value, that is, the value in the developing current storage circuit 12, that is, when the voltage was 82 (point A in FIG. 3). I judge that. Furthermore, development can be completed by setting point B, which has passed the peak voltage E, as the end point of additional development. The additional development factor may be set in the additional development factor storage circuit 13 as a predetermined time from the end of the main development as in the above example, or may be set as a percentage of time with respect to the main development. It is clear that the present invention can also be realized by further performing additional development with the point in time as the end point of the main development.

In the figure, 14 is a mechanism such as a buzzer or a timer that notifies the completion of development.

In this example, a platinum wire was used as the electrode facing the substrate 3, but any conductive material is possible, and the conductive material under the resist layer may be other metals other than chromium, such as molybdenum or tungsten, silicon, or an IC mask. etc. is of course possible.

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

According to 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 masks are conveyed by a carrier 32 into the developer 2. 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 development efficiency and improve uniformity on the mask. A conducting wire is connected to one of the plurality of masks 33 so as to be connected to chrome, which is a metal film of the mask. 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 conducting wire and the 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, thereby stirring the developer 2a and improving the developing efficiency and the uniformity of the mask development. .

As described in detail, the method of the present invention allows for highly reproducible and efficient optimal development and automation because the development status is detected electrochemically. Furthermore, the present invention enables frequency control of IC mask crystal oscillators, surface acoustic wave filters, etc.

That is, since the end point is detected electrochemically rather than visually, the reproducibility is good, and the subsequent etching can be performed with high precision, so that variations in the oscillation frequency can be reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example for explaining the present invention in detail, FIGS. 2A and 2B are schematic cross-sectional views showing the resist development process, and FIG. 4 is a graph showing the relationship between developing voltages, and FIG. 4 is a schematic diagram showing an embodiment of a developing container for carrying out the method of the present invention. 1... Container, 2... Developer, 3... Substrate, 4...
・Platinum wire, 5... Holder, 6... Conductor wire, 7a, 7b
. . . Vinyl lead wire, 8 . . . Resistor, 9 .
3... Additional development factor memory circuit, 14... Buzzer or timer, 15... Pond, 16... Starting switch, 21... Chrome layer, 22... Negative resist, 23... Negative resist (exposed area), 30...
Outer tank, 31... Inner tank, 32... Carrier, 33.
...Mask, 34...Transportation mechanism, 35...Motor,
36...Pump.

Claims (1)

[Claims] 1. A resist layer is formed on a conductor layer formed on a substrate, the resist layer is exposed to light or X-rays, or exposed to electron beams to form a desired pattern, and then In the method for detecting the end point of development of the substrate exposed to light, connecting means made of a first conductive material to the conductive layer through the resist of the substrate exposed to light or X-rays or drawn with electron beams to connect one electrode. Detecting the end point of development, characterized in that an object made of a second conductive material is immersed in a developer solution to serve as another electrode, a voltage is applied between the two electrodes, and a current flowing between the two electrodes is monitored. Method. 2. The method according to claim 1, wherein the first conductive material is made of the same material as the conductor layer. 3. A method according to claim 1, characterized in that the connecting means is immersed in a developer solution and coated so as not to come into contact with the core developer solution. 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. Claim 4, characterized in that the end point of the main development is a point in time when the rising voltage becomes smaller than a specified value.
The method described in section. 6. The method according to claim 4, wherein the end point of the main development is set at a point in time when the rate of increase in voltage decreases. 7. The method according to claim 4, wherein the change in the current is a peak value. 8. The method according to claim 4, wherein the change in current is at a maximum slope point. 9. 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.