JPH03225812A - Semiconductor manufacturing facility - 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 Application Field] The present invention relates to an apparatus for manufacturing semiconductor devices such as ICs and LSIs, and in particular, to maintain the performance thereof, a function for automatically correcting error factors is provided. The present invention relates to a semiconductor manufacturing apparatus that has a correction function and is capable of setting operating conditions for its correction function.

[Prior Art] Exposure apparatuses for manufacturing semiconductors such as ICs and LSIs are required to have three basic performances: resolution performance, overlay performance, and processing capacity. Resolution performance refers to the ability to form fine patterns on a photoresist surface applied to a semiconductor substrate (hereinafter referred to as a "wafer"), and overlay performance refers to the ability to form a fine pattern on a photoresist surface coated on a semiconductor substrate (hereinafter referred to as a "wafer"). This refers to the ability to accurately align and transfer the pattern on the photomask with the pattern formed on the surface.

Furthermore, processing capacity refers to the ability to expose and transfer patterns onto a large number of patterns within a certain amount of time.

Generally, the resolving power of exposure equipment for semiconductor manufacturing is around 0.8 μm, and devices aiming at resolution around 0.5 μm are beginning to appear. On the other hand, the overlay accuracy for burn-in requires a value of 1/3 to 115 of the minimum line width, which is 0.1 μm.
It will also be within. In such a region, subtle changes over time due to the external environment such as temperature and pressure, and operational history such as wear of parts cannot be ignored. Therefore, in order to maintain stable performance, it is essential to periodically check and correct the error factors.

Factors that are subject to such correction include the projection magnification of the lens, the focal position, the alignment position of the reticle, the arrangement coordinate system of the wafer stage, and the distance between the optical axis of the projection lens and the optical axis of the alignment optical system. Line
) etc.

-If the level of performance you are trying to maintain for boat fishing is high,
This increases the frequency of correction work and requires a lot of time, making it impractical to rely on manual labor. One way to improve this situation is to automate the correction work.

For example, using a writable and erasable photosensitive material, Ba5
There are methods such as e-line, methods that correct the array coordinate system of the wafer stage, and methods that automatically align the reticle every time a certain number of wafers are processed.

Such an automatic correction function is normally performed as follows.

Equipment operating conditions, such as time, number of wafers processed, temperature,
When the atmospheric pressure etc. reach a certain level, the normal wafer processing routine is stopped, automatic correction is performed, and then the normal wafer processing routine is stopped.
It also resumes normal wafer processing routines. Therefore, in order to increase the number of sea urchins processed, that is, the processing capacity of the apparatus, it is preferable not to perform the automatic correction operation.

[Problem to be solved by the invention] However, the automatic correction function is not effective in maintaining the performance of the device.
It is indispensable. Therefore, taking this point into consideration, the following improvements are made to improve processing performance. One is to shorten the correction time by improving the automatic correction function itself. The other is a reduction in the frequency of correction due to improved performance stability of the device.

However, the correction operation always requires a certain amount of time, and there are obvious changes in device performance over time in micron or submicron units.

Therefore, in reality, there is a need for JJ that comes from the wafer processing process!
It is important to determine the correction frequency based on accuracy, time required for automatic correction, and stability of device performance.

In view of this reality, an object of the present invention is to provide an exposure apparatus that allows correction frequency to be set by inputting a plurality of conditions.

[Means for Solving the Problems] In order to achieve the above object, the present invention determines whether a correction condition occurs at multiple locations in a program that implements normal wafer processing, and if it occurs, automatically performs correction. Inserting a sequence.

[Operation] An automatic correction routine is performed after completion of a plurality of predetermined routines of a normal wafer processing sequence. In the automatic correction routine, the necessity of correction is determined and correction conditions are set.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

Figure 'tS1 shows the external appearance of a projection exposure apparatus according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a mask having an integrated circuit pattern, and also includes mask alignment marks and mask-wafer alignment marks. 2
holds the mask 1 on a mask stage and moves the mask 1 in the plane (XY force direction and rotational direction (θ direction). 3 is a reduction projection lens, 4 is a wafer provided with a photosensitive layer, and the mask wafer alignment is performed. 5 is a wafer stage. The wafer stage 5 holds the wafer 4 and moves it in the plane and in the rotational direction, and also has a wafer baking position ( (within the projection field of view) and the TV/wafer alignment position. 6 is the objective lens of the TV/wafer alignment detection device, 7 is the image pickup tube (or solid image sensor). 9 is the binocular unit, and the projection lens 3
This is useful for observing the surface of the wafer 4 through the wafer 4. 10
is the upper unit housing the illumination optics and sensing equipment for mask-wafer alignment. 11 is a monitor receiver (console CRT), and 12 is a keyboard for inputting various operating commands and parameters in the apparatus.

FIG. 2 shows the electrical circuit configuration of the device of FIG.

In the figure, 21 is the main body CPU that controls the entire device.
It consists of a central processing unit such as a microcomputer or minicomputer. 22 is a wafer stage drive device, 23 is an alignment detection system, 24 is a reticle stage drive device, 25 is an illumination system, 26 is a shutter drive device, 27 is a focus detection system, and 28 is a 2 drive device, which are controlled by the main CPU 21. controlled. 29 is a conveyance system.

Reference numeral 30 denotes a console unit for giving various commands and parameters regarding the operation of the exposure apparatus to the main body CPU 21. 31 is a console CPυ, and 32 is an external memory for storing parameters and the like. In addition, CRT
II and keyboard 12 are identical to those in FIG.

33 is an environmental sensor. It consists of a thermometer, barometer, hygrometer, accelerometer, clock, counter, etc., and is used to determine the occurrence of automatic correction conditions, which will be described later.

As shown in FIG. 3, the apparatus shown in FIG. 1 enters a command input waiting state (step 41) when initialization after power-on is completed (step 40). That is, the console CPU 31 waits for a key operation on the keyboard 12, and the main body CPU 21 enters a state of waiting for communication from the console CPU 31. At this time, the CRTII displays the screen shown in FIG. 4, for example. When a command (for example, CC5) for setting correction conditions is entered manually from the keyboard 12 in this state, the following correction condition setting process (step 42) is started under the control of the console CPU 31.

The correction condition setting process will be explained with reference to the flowchart in FIG. 5 and the display screen example in FIG. 6. At step 41 in FIG. 3, when a command for setting correction conditions is entered manually, the process proceeds to step 50. In step 50, items to be automatically corrected are displayed as shown in FIG. 6(a),
Furthermore, a prompt is displayed to indicate that one of the items should be selected by number. When one of these item numbers is selected,
The process advances to step 51, and the display screen is switched to the one shown in FIG. 6(b). Here, the selected item and the conditions to be changed or set are displayed, and a prompt to select one of the conditions by number is also displayed. When any condition number is selected in accordance with this display, a prompt message prompting the user to input the condition is displayed as shown in FIG. 6(C). Here, when the conditions are entered manually from the keyboard 12, the correction conditions are updated based on this, and the screen becomes as shown in FIG. 6(d). This display is the same as that shown in FIG. 6(C), except that it shows updated conditions.

If there are any other conditions that you would like to change or set, enter their condition numbers and set the conditions in the same manner as above.

If you want to finish setting the conditions for this item, press r from keyboard 12 in response to the prompt message.
If H, is input, the process returns to step 50.

If conditions are to be changed or set for other items, the same steps as described above are made. Further, to end the condition setting, input r E J from the keyboard 12 and return to step 41 in the command input waiting state.

Next, an example of automatic correction during normal wafer processing will be shown with reference to FIGS. 7 and 8.

FIG. 7 is a flowchart in which automatic correction processing is incorporated at multiple locations in a sequence for performing normal wafer processing. In the figure, the parts labeled Pi to Pl2 are the parts that undergo automatic correction processing. The symbol Pn in the ia diagram corresponds to any one of Pl to Pl2.

In the command waiting state (step 41), a command (for example, ST) for starting wafer processing is manually input. This starts the wafer processing sequence shown in FIG. 347.

First, the first automatic correction portion P1 is executed. The processing at Pl is shown in FIG. 8.

In step 91, it is determined whether there are any items to be automatically corrected. According to the example of FIG. 6(a), the objects to be corrected in Pl are the baseline and the wafer arrangement coordinate system. Therefore, the process proceeds to step 92 in which it is determined whether a correction condition has occurred. Here, as shown in FIG. 6(d), the correction condition is correction at startup, that is, at
It is assumed that the condition for 5tart is specified as Yes. In this case, it means that the correction condition has occurred, so the process proceeds to correction sequence execution step 93.The correction sequence in this case may be, for example, one using a writable and erasable photosensitive material. When this process is completed, wafer processing is restarted toward steps 60 and 70.

The process shown in the flowchart in FIG. 7 is executed below, and the symbol P
1 to the automatic correction execution part indicated by Pl2, the 8th
Execute the automatic correction process shown in the figure. For example, in Figure 6 (
In the case of the correction item baseline shown in d), Pl and P3
This section is a correction item. Therefore, when the sequence reaches part p3, the process proceeds from step 91 to step 92, where it is determined whether a correction condition has occurred. In this example, the correction conditions are every 20 wafers processed or one hour has passed since the last correction, so if either of these conditions occurs, the process advances to step 93 and automatic correction is performed.
After performing the baseline correction), wafer processing (step 62) is restarted. If neither condition occurs, the process proceeds to step 62. In the subsequent automatic correction portion, the baseline is not a correction item, so no correction is performed. When the wafer processing sequence returns to the Pl portion, baseline correction will be performed according to the conditions. Thereafter, wafer processing and automatic correction are repeated in the same manner.

[Effects of the Invention] As explained above, according to the present invention, the correction execution conditions can be set, so that the optimum conditions can be set from the viewpoints of the necessary accuracy resulting from the processing process, the time required for automatic correction, and the stability of device performance. You can set the correction frequency.

[Brief explanation of drawings]

FIG. 1 is an overview diagram of a projection exposure apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram showing a control circuit of the projection exposure apparatus of the above embodiment, and FIG. 3 is a diagram showing the operation of the above embodiment. FIG. 4 is a CRT screen display screen in one step of FIG. 3. FIG. 5 is a flowchart for explaining the setting of automatic correction conditions in the above embodiment. a) to (d) are each display screen in the flow of FIG. 5, FIG. 7 is a flowchart of the entire wafer processing for explaining the execution of automatic correction in the above embodiment, and FIG. 8 is a flow chart of the entire wafer processing. 7
3 is a flowchart of an automatic correction sequence portion in the flowchart of the figure. 1 2 1 0 3: CRT. : Keyboard, two CPUs. :Console unit, :Environmental sensor

Claims (2)

[Claims] (1) A CPU that executes a wafer processing sequence consisting of a plurality of steps, a correction mechanism that selectively executes a plurality of correction items, and a detection means for a plurality of correction conditions; A semiconductor manufacturing apparatus characterized in that an automatic correction step is provided between the steps, and in the automatic correction step, presence or absence of a correction item and correction conditions are determined, and a correction operation is performed according to the determination result. (2) The semiconductor manufacturing apparatus according to claim 1, wherein the correction items and correction conditions can be input to the CPU before executing the sequence.