JPH02271516A - Aligner - Google Patents

Abstract

PURPOSE:To prevent a large quantity of defective semiconductor substrates from being exposed until an abnormality is discovered by a method wherein uneven parts on the surface of a semiconductor substrate inside an exposure field are detected automatically and this detected value is judged after it has been compared with a standard value. CONSTITUTION:In an exposure treatment process of the surface of a semiconductor substrate, the following are included: roughness detection processes 8 to 10 at each exposure field on the surface of the semiconductor substrate; computation processes 11 to 13 of an amount deviated from a reference face; a process 13 to judge whether a detected result is within a standard or not. Accordingly, it is not required to execute this inspection by stopping a main operation; even when an uneven part on the surface of the semiconductor substrate is outside of the standard, it is possible to issue an alarm to stop an aligner. Thereby, even in an automated process it is possible to prevent a large quantity of defective semiconductor substrates from being exposed until an abnormality is detected at an inspection after a developing operation.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to an exposure apparatus that is equipped with a means for preventing focus shifts caused by unevenness on the surface of a semiconductor substrate. The purpose of the present invention is to provide an exposure apparatus that is capable of calculating and storing information, and the light rays emitted from a light source and transmitted through the transparent part of the reticle are reduced by a reduction lens system and applied to a resist film formed on the surface of a semiconductor substrate. An exposure apparatus for irradiating, a means for detecting irregularities for each exposure field on the surface of the semiconductor substrate placed R on a stage, and calculating an amount of deviation between the value of the irregularity and a reference surface determined from the value of the irregularity. and a memory means for storing the value of the amount of deviation for each exposure field.

[Industrial application field]

The present invention relates to an exposure apparatus equipped with means for preventing defocus caused by unevenness on the surface of a semiconductor substrate.

In recent reduction projection exposure apparatuses equipped with reduction lens systems, focal shifts occur due to local unevenness on the surface of a semiconductor substrate.

Under the circumstances described above, there is a need for an exposure apparatus that can perform exposure appropriate to the value of the local unevenness on the surface of the semiconductor substrate.

[Conventional technology]

A conventional exposure apparatus will be explained with reference to FIGS. 4 to 6.

FIG. 4 is a side view showing the schematic structure of the exposure device. In the figure, the light ray 1a emitted from the light source 1 enters the reticle 2, and the light ray 1a transmitted through the transparent part of the reticle 2 is reduced by the reduction lens system 3. The resist film 15 formed on the surface of the semiconductor substrate 14 placed on the stage 4 is normally irradiated in units of an exposure field of 20 m in diameter.

FIG. 5 is a plan view showing a schematic structure of a transport mechanism that automatically supplies and takes out semiconductor substrates 14 to and from the stage 4 of this exposure apparatus.

In the figure, a semiconductor substrate 14 taken out from a storage container 5 that stores semiconductor substrates 14 on the supply side is transported to an intermediate stage 7, where an orientation flan (1) provided on the semiconductor substrate 14 is conveyed to an intermediate stage 7.
4a as a reference.

The semiconductor substrate 14 mounted on the stage 4 that has completed the exposure process and the semiconductor substrate 14 positioned on the intermediate stage 7 are each transported by a transport tool (not shown) and their mounting positions are exchanged, and then The semiconductor substrate 14 mounted on the intermediate stage 7 that has completed the exposure process is stored in the storage container 6 that stores the semiconductor substrate 14 on the extraction side.

FIG. 6 is a process diagram of such an exposure apparatus.

First, it is checked in the "semiconductor substrate standby method" step whether or not the semiconductor substrate 14 to be processed is mounted and positioned on the intermediate stage 7, and if No, the "standby processing" step of the semiconductor substrate 14 is performed. If the answer is Yes, the above-described "replacement process" process for the semiconductor substrate 14 is performed.

Next, the semiconductor substrate 14 that has undergone the above-described exposure process is stored in the storage container 6 on the removal side [unloading process].
Semiconductor substrate 14 that has undergone the process and completed the next exposure process
A "standby process" step is performed so that the intermediate stage 7 can be loaded with the "standby process".

The semiconductor substrate 14 mounted on the stage 4 checks whether the resist film 15 formed on its surface has been exposed in the previous step in the "overlay exposure method or not" step. If so, the "step repeat exposure" process is performed without performing the "alignment" process, and if Yes, the "step repeat exposure" process is performed after the "alignment" process.

Check whether the above steps have been performed on all semiconductor substrates 14 or not.
A check is made in the process of ``Whether all semiconductor substrates have been completed or not'', and if No, the process returns to the process of ``Whether or not semiconductor substrate standby method is used'' and processing of the next semiconductor substrate 14 is started. If YES in the step ``Whether all semiconductor substrates have been completed?'', the operation of the exposure apparatus is terminated.

In the exposure process of the semiconductor substrate 14 carried out using such an exposure apparatus, in order to measure the unevenness occurring on the surface of the semiconductor substrate 14, which is usually about 2 μm, the semiconductor substrate 14 is processed in a process different from the above-mentioned main process. A "semiconductor substrate flatness measurement" process, in which only the center of the exposure field is measured, must be performed for every 14 semiconductor substrates according to instructions from the operator of the exposure apparatus.

In the exposure process of the semiconductor substrate [j14] performed using such an exposure apparatus, if the surface of the semiconductor substrate 14 is uneven, the light beam 1a is focused on the surface of the resist film 15 on the surface of the semiconductor substrate 14. The correction is made by moving the stage 4 on which the semiconductor substrate 14 is placed in the vertical direction so as to tie the two.

Furthermore, if the surface of the semiconductor substrate 14 is tilted in only one direction, the stage 4 is tilted so that the semiconductor substrate 14
Exposure is performed by performing tilt correction to make the slope of the surface horizontal.

However, if the unevenness of the surface of the semiconductor substrate 14 in the exposure field of the exposure apparatus is not sloped in only one direction, it is impossible to correct the slope using the conventional correction method, so exposure is performed without performing slope correction. Is going.

[Problem to be solved by the invention]

In the conventional exposure equipment that exposes a large number of semiconductor substrates as described above, even when it is possible to detect irregularities on the surface of the semiconductor substrate, the operator of the exposure equipment must give instructions for each semiconductor substrate. First, in order to perform this detection, the main work must be stopped and the flow of the main work stagnates. Therefore, it is impossible to detect unevenness on all semiconductor substrates, and it is not possible to perform the automated process. In the event that the unevenness of the semiconductor substrate surface deviates from the standard, a large number of defective semiconductor substrates will be exposed until the semiconductor substrate reaches the inspection process after the development process and the abnormality is discovered. There was a problem with this.

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, it is an object of the present invention to provide an exposure apparatus that can detect, calculate, and store irregularities on the surface of a semiconductor substrate without disrupting the main work flow.

[Means to solve the problem]

The exposure apparatus of the present invention is an exposure apparatus that reduces a light beam emitted from a light source and passes through a transparent part of a reticle using a reduction lens system, and irradiates the resist film formed on the surface of a semiconductor substrate, and the exposure apparatus is mounted on a stage. means for detecting the unevenness of the surface of the semiconductor substrate for each exposure field, means for calculating the amount of deviation between the value of the unevenness and a reference surface determined from the value of the unevenness, and means for detecting the deviation for each exposure field. and memory means for storing the value of the quantity.

[Effect]

That is, in the present invention, during the normal exposure process of the surface of a semiconductor substrate, there is a step of detecting unevenness for each exposure field on the surface of the semiconductor substrate, a step of calculating the amount of deviation from the reference surface, and a step of detecting that the detection result falls within the standard. This eliminates the need for the operator to instruct the exposure equipment for each semiconductor substrate and to stop the main operation to perform this detection. If it deviates from the standard, it is possible to issue an alarm and stop the exposure equipment, so even in an automated process, it is possible to eliminate a large number of defective semiconductor substrates before an abnormality is discovered during post-development inspection. It becomes possible to prevent exposure to light.

〔Example〕

An exposure apparatus according to an embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

The schematic structure of the exposure apparatus used in this example is shown in Figures 4 and 5.
This is the same as the conventional exposure apparatus shown in the figure.

FIG. 1 is a process diagram of an exposure process using such an exposure apparatus.

"Whether or not it is a semiconductor substrate standby method" and "standby processing" shown in the figure.
"Exchange processing", "unload processing", and "standby processing" are the same as the conventional process.

Also, "whether overlapping exposure has been completed", "alignment",
"Step repeat exposure" is also the same as the conventional process.

In an exposure apparatus according to an embodiment of the present invention, a process as shown in FIG. 2 is added to the position indicated as rAJ, rBJ, or "C" in FIG. 1.

The details of the rAJ, r[3J, rcJ process are as shown in FIG. "Calculating the amount of deviation from the reference surface" step of calculating the amount of deviation from the reference surface obtained by the square method;
In the "Whether or not the deviation amount is within the standard" process that determines whether or not it is within the preset standard, if Yes, the process continues, and if No, after the "alarm is generated", the equipment starts operating. stop.

Note that when inserting the process shown in Figure 2 at the rCJ position, the automatic focusing data from the previous "step repeat exposure" process can be used, so the "semiconductor substrate surface unevenness detection" process is omitted. be able to.

The best insertion position for the process shown in Figure 2 is rBJ.
The position of rAJ is before the "alignment" process and the position of the semiconductor substrate 14 has not yet been determined, and the position of "C" is the position of the semiconductor substrate 14 after the "step repeat +-i light" process. Because it is later, it is the next best insertion position.

After the above steps are completed, "Whether or not all semiconductor substrates are finished?"
The process is also the same as the conventional process.

FIG. 3 is a block diagram of a mechanism for correcting unevenness of a semiconductor substrate in an exposure apparatus according to an embodiment of the present invention.

The analog data of the unevenness detected by the detector 8 and focused on each center of the entire exposure field for one semiconductor substrate 14 is controlled by an automatic gain controller 9 (hereinafter abbreviated as AGC 9). Then, it is converted into digital data by an A-D converter 10 and stored in a memory 11. Using this digital data, the main processor 13 calculates the amount of deviation of the center of each exposure field from the reference plane, and stores the digital data of the entire exposure field of the semiconductor substrate 14 in the memo January 2 added in this embodiment. Then, based on this digital data, the amount of deviation from this reference plane is compared with a standard value, for example, 1.0 μm, and the main processor 13 judges whether it is greater than or not. The stage 4 is controlled to adjust the focus, and if the focus is exceeded, the operation of the exposure apparatus is stopped.

In the exposure process of the semiconductor substrate 14 performed using such an exposure apparatus, the process shown in FIG. Since this measurement can be performed on all the semiconductor substrates 14, it is possible to perform appropriate focusing for each exposure field of the semiconductor substrate 14.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, there is no need for frequent operations by an operator, and the exposure apparatus automatically detects the unevenness of the semiconductor substrate surface within the exposure field, and uses the detected value and the standard. It is possible to make a judgment by comparing the values and to issue an alarm in the event of an abnormality and automatically stop the exposure equipment.If automated, it is possible to eliminate a large number of defective semiconductor substrates by the time the abnormality is discovered. It is possible to provide an exposure apparatus that can be expected to be significantly economical and to improve reliability.

[Brief explanation of drawings]

FIG. 1 is a process diagram of an exposure apparatus according to an embodiment of the present invention, FIG. 2 is a detailed diagram of an additional process of an embodiment according to the present invention, and FIG. 3 is a semiconductor substrate in an exposure apparatus according to an embodiment of the present invention. 4 is a side view showing the schematic structure of the exposure device, FIG. 5 is a plan view showing the schematic structure of the semiconductor substrate transport mechanism of the exposure device, and FIG. 6 is a conventional exposure device. The process diagram is as follows. In the figure, ■ is a light source, 1a is a light beam, 2 is a reticle, 3 is a reduction lens system, 4 is a stage, 5 is a storage container, 6 is a storage container, 7 is an intermediate stage, 8 is a detector, and 9 is an AGC. IO is an A-D converter, 11 is a memory, 12 is a memory, 13 is a main processor, 14 is a semiconductor substrate, 14a is an orientation flat, and 15 is a resist film. A process diagram of an exposure apparatus according to an embodiment of the present invention. A side view showing a schematic structure of an exposure apparatus. Detailed coverage diagram Process diagram of conventional exposure equipment

Claims (1)

[Claims] The light beam (1a) emitted from the light source (1) and transmitted through the transparent part of the reticle (2) is reduced by the reduction lens system (3), and the resist film (1a) formed on the surface of the semiconductor substrate (14) is reduced.
15) An exposure apparatus for irradiating a semiconductor substrate (14) placed on a stage (4), comprising means for detecting irregularities for each exposure field on the surface of the semiconductor substrate (14) placed on a stage (4), and a means for detecting irregularities for each exposure field; An exposure apparatus comprising: means for calculating the amount of deviation from a reference plane; and memory means for storing the value of the amount of deviation for each exposure field.