JPH0311726A - Exposure device of wafer periphery - Google Patents

Abstract

PURPOSE:To enable a wafer periphery to be exposed with high precision in a relatively simple constitution by a method wherein the peripheral position data on a wafer are collected by a linear image sensor to decide the displacement of an exposing light source based on the said data. CONSTITUTION:A CCD line sensor 6 continuously detects the peripheral positions of a wafer W by a driving circuit 9 regardless of a pulse motor 2 so as to successively feed detection signals to a signal processing circuit 10. The circuit 10 outputs the analog signals proportional to the picture element numbers of the sensor 6 detecting the irradiating beams from a light source 7 so that the analog signals may be fed to an A/D converter 11 receiving the data pick up timing signals (a) from a CPU 12 so as to be digitized and stored in a RAM 13 as the peripheral position data. On the other hand, the CPU 12, a pulse generator circuit 14 and a counter 16 control the step feed of the motor 2 while another pulse generating circuit 17 controls another pulse motor 5 based on the revolution data (c) during exposure times informed of the displacement of an exposing light source 3 by the CPU 12.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is applied to a wafer periphery for removing photoresist coated on the surface of a wafer such as a semiconductor wafer or a ceramic wafer. The present invention relates to a wafer peripheral area exposure apparatus that exposes a peripheral area of a wafer.

<Prior art> It is known that when handling wafers coated with photoresist, the photoresist around the wafer may adhere to the handling equipment and scatter, potentially contaminating the wafer surface and handling equipment. There is. Therefore, before or after forming a pattern on the wafer surface coated with a photoresist, particularly a positive type photoresist, the periphery of the wafer is exposed to light to remove the photoresist in that area.

The periphery of the wafer consists of a circular arc portion and a straight line portion called an orientation flat, and the exposure of the wafer periphery described above is performed over the entire periphery consisting of the circular arc portion and the orientation flat portion.

As such a wafer periphery exposure apparatus, for example, a positioning device as disclosed in Japanese Patent Application Laid-open No. 60-80241 is used to align both ends of the orientation flat of a wafer that is suctioned and held on a table and rotated. is detected by an optical sensor, and the rotation angle p of the table at that time is
, P, are determined, the wafer is positioned based on the position of (P1+P2)/2, and the exposure light source is moved along a temporary cam that rotates in phase with the wafer in synchronization with the wafer. There is an apparatus that exposes the circular arc portion and the orientation flat portion of the positioned wafer with substantially the same width.

Furthermore, a position detection device such as that disclosed in Japanese Patent Application Laid-Open No. 61-276229 is used to detect the rotation angle of a wafer held by suction on a table, and a one-dimensional image sensor is synchronized with this angle detection signal. It is also conceivable to obtain discrete positional information on the outer periphery of the wafer by scanning the wafer, and then to expose the periphery of the wafer by displacing the exposure light source based on this positional information, as in the former apparatus.

<Problems to be Solved by the Invention> However, the above-described conventional device has the following problems.

According to the former type of exposure equipment, if the wafer is placed eccentrically on the table or if two or more orientation flats are formed on the wafer, the wafer cannot be aligned correctly. There is a problem that the exposure width around the periphery is not constant.

On the other hand, with the latter type of exposure equipment, position information can be obtained over the entire periphery of the wafer, so the above-mentioned problems can be considered to be solved, but since it is necessary to detect the rotation angle of the wafer, the angle It is necessary to include a low-resolution encoder, a resolver, etc. as a detector, which creates a problem with Betsutaku in that the device becomes complicated and expensive.

The present invention has been made in view of the above circumstances, and provides a wafer periphery exposure apparatus that can obtain positional information around the wafer and expose the wafer periphery with high precision using a relatively simple configuration. is intended to provide.

Means for Solving the Problems> In order to achieve the above objects, the present invention has the following configuration.

That is, the present invention is a wafer peripheral exposure apparatus that exposes the periphery of the wafer with an exposure beam while rotating a wafer coated with photoresist, comprising: wafer rotation driving means for rotationally driving the wafer; Rotary drive control means for stepping the wafer rotation drive means at a predetermined angle; a light source for irradiating an exposure beam; light source displacement means for relatively displacing the positional relationship between the light source and the wafer; and the wafer. a one-dimensional image 'sensor for detecting the peripheral position of the image sensor; a data capture timing control means for providing a timing for capturing the peripheral position data from the one-dimensional image sensor when the step feeding is stopped; a storage means for storing data; and a light source displacement control means for controlling the displacement amount of the light source displacement means based on the peripheral position data of the wafer stored in the storage means for each step of the wafer rotation drive means during exposure. It is prepared.

Effect〉 The effects of the present invention are as follows.

When sampling peripheral position data of the wafer, the wafer rotation drive means steps forwards the wafer at a predetermined angle based on a command from the rotation drive control means. The data capture timing control means controls the data capture timing so as to capture peripheral position data when the step feeding is stopped, out of the peripheral position data continuously output from the one-dimensional image sensor. The captured peripheral position data is stored in the storage means in association with each step angle.

During exposure, the light source displacement control means reads peripheral position data corresponding to each step angle from the storage means every time the rotational drive control means advances the step angle during exposure, and adjusts the position for exposure based on the peripheral position data. The amount of displacement of the light source is calculated to control the light source displacement means. As a result, the exposure light source is displaced according to the peripheral shape of the wafer, so that the exposure beam is irradiated along the periphery of the wafer.

<Example> Hereinafter, an example of the present invention will be described in detail based on a concave surface.

FIG. 1 is a block diagram showing a schematic configuration of a wafer peripheral exposure device according to an embodiment of the present invention, and FIG. is on the table! ! A plan view of the placed wafer, and the fourth part (b) is a side view of the exposure section.

In FIG. 2, reference numeral 1 denotes a table that attracts and holds a wafer W, and this table 1 is rotationally driven by a pulse motor 2 serving as wafer rotation driving means. 3 is an exposure light source for exposing the periphery of the wafer. The light source 3 is screwed onto a screw shaft 4, and is configured to be able to displace the light source 3 in the radial direction of the wafer W by a pulse motor 5 as a light source displacement means connected to the screw shaft 4. At a position facing the light source 3 across the table l, there is a CC as a one-dimensional image sensor that detects the peripheral position of the wafer W.
A D-line sensor 6 is provided, and above the CCD line sensor 6, a light source 7 and an optical system 8 for peripheral position detection are provided.
is provided. The CCD line sensor 6 is connected to the wafer W.
so that their centers match the table l! ! 2
The edge of the circular arc portion of the wafer W is placed in the center of the effective pixel area of the CCD line sensor 6 when the wafer W is placed.

Please refer to FIG. The CCD line sensor 6 continuously detects the peripheral position of the wafer W by the CCD drive circuit 9, regardless of (asynchronously) the rotation of the pulse motor 2.
The detection signal is sequentially given to the signal processing circuit 10. C
Based on the detection signal from the CD line sensor 6, the signal processing circuit 10 outputs an analog signal proportional to the number of pixels of the CCD line sensor 6 that received the irradiated light from the light [7.

This analog signal is given to the A/D converter 11. The CPU 12, which has a function as a data acquisition timing control means, provides a data acquisition timing signal to the A/D converter 11, and the input analog signal is converted into a digital signal based on this timing signal. This digital signal is transmitted to the CP as peripheral position data of the wafer W.
It is stored in the RAM 13 via U12.

The CPU 12, the pulse generation circuit 14, and the counter 16 correspond to rotational drive control means for controlling the step feed of the pulse motor 2, and the pulse generation circuit 14 controls the pulse motor drive circuit 15 based on the rotation speed data given from the CPLJ 12. Output the required number of pulse signals. The counter 16 is a programmable counter to which the CPU 12 receives the rotation speed data as a preset signal.
Output to 12.

The CPU 12 and the pulse generation circuit 17 use the exposure light S3
The pulse generating circuit 17 drives and controls the pulse motor 5 via the pulse motor drive circuit 18 based on the rotation speed data during exposure given from the CPU 12.

Next, a procedure for sampling peripheral position data of the wafer W will be described with reference to the flowchart shown in FIG.

When wafer W is set on table l, CPtJ12
outputs a peripheral position data acquisition timing signal to the A/D converter 11. As a result, the sampling point where the θ address is 0°, that is, the CCD line sensor 6
The peripheral position data of the point that was initially facing the CPU 12
is stored in the RAM 13 via (step Sl).

When the first peripheral position data is taken in, the CPU 12 determines the step feed angle for data sampling (for example,
9°) is given to the pulse generating circuit 14, and this rotation number data is preset in the counter 16. As a result, the pulse generation circuit 14 outputs a number of pulse signals corresponding to the rotational speed data and the pulse motor 2 is driven, so that the wafer W is fed in steps by a predetermined angle (step S2).

When the set number of pulse signals are output, counter 1
6 outputs a count-up signal to the CPU 12. Based on this count-up signal, the CPU 12 determines whether the pulse motor 2 has stopped (step S3).

When the pulse motor 2 stops, the CPU 12 outputs a data acquisition timing signal to the A/D converter 11, acquires peripheral position data of the next sampling point, and stores this in the RAM 13 (step S4).

When the peripheral value 1 data is taken in, the CPU 12 determines whether the peripheral position data around the entire wafer has been taken in, that is, whether the pulse motor 2 has been rotated through 360 degrees (step S5). If not, the operations of steps S2 to S4 are repeated.

In the manner described above, discrete peripheral position data over the entire periphery of the wafer W is collected. FIG. 5 shows the collected surrounding position data. Since the wafer W is normally placed somewhat eccentrically with respect to the center of the table l,
The peripheral position data changes smoothly around the reference position (peripheral position data of the wafer arc portion when the wafer center and the table center coincide). Further, the region in FIG. 5 shows peripheral position data of the orientation flat portion.

When the collection of peripheral position data around the entire periphery of the wafer W is completed, in this embodiment, interpolation processing is performed between each piece of discrete peripheral position data (step S6).

If the step feed angle during data sampling is set small enough, there is no need to perform interpolation processing, but if the step feed angle is set slightly larger to shorten the time required for data collection, It is preferable to perform data interpolation processing in order to smoothly trace the exposure beam along.

Although the method of interpolation processing is not particularly limited, in this embodiment, as for the peripheral position data of the circular arc portion of the wafer W, as shown in an enlarged view in FIG. (indicated by an x in the figure),
The peripheral position data of each interpolation point is calculated by linear interpolation.

Linear interpolation may also be used between sampling points near the edges of the orientation flat, but in this case the exposure width at the edges of the orientation flat will be wider than other parts, so in this example, these sampling The points are interpolated as follows.

Figure 7 (a) is an enlarged view of the peripheral position data near the orientation flat part of the peripheral position data shown in Figure 5. In Figure 6, the broken line indicates the peripheral position obtained by linear interpolation. The positional data profile, the dashed line, is a profile showing the actual wafer periphery. As is clear from the figure, at the orientation flat end, the error between the profile of the linear interpolation and the actual profile around the wafer is considerably large. Due to this error, according to linear interpolation, the exposure width at the edge of the orientation flat becomes wider than the other exposure areas (indicated by diagonal lines) by the area B shown in FIG. 7(C).

Therefore, as shown in an enlarged view in FIG. 7(b), for example, sampling points P and P, with the end of the orientation flat sandwiched therebetween. 1, the data of each interpolation point from the peripheral position data P to the interpolation point r1 corresponding to the orientation flat end F1 is
Set equal to the peripheral position data of the sampling point P,
From interpolation point r1 to sampling point P1. ．． Until now, peripheral position data had been calculated by linear scanning. Similar interpolation processing is performed for the other orientation flat end F8.

In such processing, in order to determine the interpolation points fl and fx, the end position F+ of the orientation flat,
Fz is calculated as follows.

This will be explained below with reference to FIG. Figure 8 shows table l
In the figure, OH is the center of the wafer, 0 is the center of the table, and P is the center of the table.

˜P□, indicates sampling points around the orientation flat portion, θ, ˜θ1, and θ addresses corresponding to rotation angles of each sampling point.

In this embodiment, the perpendicular line σ drawn from the table center O to the orientation flat is used as the reference line, and the opening angle r++ γ2 from this reference line represents the ends F+ and Fz of the orientation flat, respectively. Therefore, first, the position of the reference line is calculated as follows.

[1] Reference line position calculation process■ First, find the sampling point with the largest peripheral position data from among the collected peripheral position data.The 0 peripheral position data is large enough that the CCD line sensor 6 receives light over a wide range. Therefore, the sampling point with the largest peripheral position data is included in the orientation flat portion unless the wafer W is placed on the table 1 with extreme eccentricity. Here, the θ address is θ1.
4 sampling point P1. ．． Suppose that is detected.

■ Next, the sampling P1. ．． Appropriately select sampling points within the orientation frame and throat between the sampling points sandwiching the . This is determined by selecting a sampling point that is a predetermined step angle away from the θ address of the sampling point with the largest peripheral position data. Here, P. θ1, which is two step angles away from 4. and each sampling point P of θ114&. Suppose that 2 and P 116& are selected.

■ Let α be the opening angle of clove, 2 and Otsu, then the length of the reference line section is expressed by the following formula.

σte=? T”P, , Co58 = rL, &cos
(cx -8)...(1) σ7a+t+ σ Below, 1 is the distance from the center of the table to the center position of the CCD line sensor 6, and the distance between each sampling point P, 2 and P, . Surrounding position data D+
It can be easily determined by subtracting s+f + D@hh, respectively, and α is θ1. h-○,. It is given by 8. Moreover, β is the θ address 0 of the sampling P□mushroom.
The opening angle of the reference line section with respect to 1 is shown.

From the above equation (1), the following equation (2) for calculating the position β of the reference line is obtained.

...... (2) [2] Orientation flat edge position calculation process Position γ1 of the orientation flat edges F, , Fl with respect to the reference line calculated as in [1] above.
γ2 is calculated as follows.

■ The rate of change of 0 peripheral position data that selects the sampling point showing the largest value of the rate of change of peripheral position data in the vicinity of sampling point P1.4 indicating the maximum peripheral position data selected in (1)■ above. is the largest at the orientee silane flat end F+, Fg
Here, the sampling point P whose θ address is θ, and the sampling point P whose θ address is θ1. ．．
The sampling point P0. ．． Suppose that is selected.

■ 1. ! =tn, ? lr, 'in
, , , can be approximated by can do.

From the positions of the ends F, , F, of the orientation siding flat determined as above, Fl.

The interpolation point f+', fz closest to F8 is determined.

Next, the peripheral exposure process of the wafer W will be described with reference to the flowchart shown in FIG.

For sampling of peripheral position data, wafer W is
By rotating, the wafer W has returned to its initial setting. Since the light source 3 is installed opposite to the installation position of the CCD line sensor 6, which is the standard for the θ address of the sampling point, the θ address is 18 for exposure processing.
The peripheral position data of the 0° sampling point is first read out.

As shown in FIG. 2(a), the distance j! between the reference position C of the exposure light fi3 and the center 0 of the table 1! Since llt, , is set in advance, the distance of the light source 3 from the reference position C,
-L, and is driven by a preset exposure width. Then, the exposure position is corrected based on the peripheral position data of the sampling point whose θ address is 180@.

The CPU 12 outputs rotation speed data for displacing the light source 3 to the exposure position determined as described above to the pulse generation circuit 17 (step N1).

When the initial position setting of the light 'a3 is completed, the CPU 12
The rotation speed data for rotating the wafer W by 0.9'' from the exposure start point with the θ address of 180'' is output to the pulse generation circuit 14, and the rotation speed data is preset to the counter 16. As a result, the pulse generation circuit 14 outputs a number of pulse signals corresponding to the rotational speed data, and the wafer W is rotationally displaced by 0.9° (
Step N2).

When the wafer W rotates 0.966 times and the counter 16 counts up, the CPU 12 determines that the θ address is 180 +
The peripheral position data of the 0.9° interpolation point is read from the RAM 13, and the rotation speed data corresponding to this data is output to the pulse generation circuit 17, thereby setting the position of the light source 3 anew (step N3).

Then, it is determined whether or not the exposure of the pre-specified area has been completed (step N4). If not, the exposure processing of steps N2 to N3 is repeated.

When the peripheral exposure of the designated area is completed, the light 'a3 is turned off and returned to the reference position C (step N5).

Although the peripheral exposure of the wafer W is completed by the above processing,
In this embodiment, in order to determine whether the pulse motor 2 for driving the wafer rotation has stepped out or the setting position of the wafer 1W has shifted during the above processing, steps N6 to N8 are performed. There is.

That is, the wafer W whose peripheral exposure has been completed is set as the sampling start point of peripheral position data, and the peripheral position data at that position is sampled again (step N6), and the peripheral position data sampled first and this time are It compares the peripheral position data and determines whether the error is within the permissible range (step N7). If it is not within the permissible range, it is determined that the wafer W has not been correctly peripherally exposed. An error message is displayed to alert the operator (step N8).

In the above embodiment, a mechanism for driving the light source 3 toward the center of the table 1 was used as the light source displacement means for relatively displacing the positional relationship between the light source 3 and the wafer W.
The light source 3 may be fixed and the table 1 may be horizontally displaced.

Furthermore, the light source displacement means is not limited to one that displaces the light B3 only in one axis direction as in the above embodiment, but may be configured to horizontally displace the light B3 independently on two orthogonal axes. According to the light source displacement means, when exposing the circular arc portion around the wafer, the light/IR3
When exposing the orientation flat portion of the wafer 1 in a straight line using a drive mechanism that displaces the light source toward the center of the table 1, it is necessary to displace the light source in a direction perpendicular to the drive mechanism. By using one drive mechanism, the edges of the orientated chiron flat can be exposed with higher precision.

Furthermore, in the embodiment, the case where the periphery of the wafer W is exposed to light with a constant width has been explained as an example, but for example, when the exposure width of a predetermined part of the wafer periphery is exposed to be wider than other parts. It can also be applied to

<Effects of the Invention> According to the present invention, the peripheral position data of the wafer is collected using a one-dimensional image sensor, and the amount of displacement of the exposure light source is determined based on this peripheral position data, so that the wafer is not biased toward the table. Even if the wafer is carefully aligned or the wafer has two or more orientation flats, the periphery of the wafer can be exposed accurately.

Further, the wafer peripheral area exposure apparatus according to the present invention allows the one-dimensional image sensor to continuously move by itself, and when the step feeding of the wafer stops, the peripheral position data is collected from the one-dimensional image sensor. 6, there is no need for an angle detector such as a rotary encoder or resolver to detect the rotation angle of the table, which was required in the conventional device that scans a one-dimensional image sensor in synchronization with the rotation angle of the wafer. The device can be constructed easily and inexpensively.

Furthermore, according to the present invention, since the signal from the one-dimensional image sensor is taken in when the wafer is stopped, for example, light detection is performed in order by scanning each pixel like a MOS image sensor. Even if such a sensor is used, that is, a sensor that requires a considerable amount of time to detect light from all pixels, it is possible to accurately read the peripheral position data of the wafer.

[Brief explanation of drawings]

1 to 8 are explanatory diagrams of one embodiment of the present invention, in which FIG. 1 is a block diagram showing a schematic configuration of a wafer peripheral area exposure apparatus, FIG. 2 is a configuration diagram of an exposure section, and FIG. Figure 3 is a flowchart showing the procedure for sampling peripheral position data, Figure 4 is a flowchart showing the procedure for exposure processing, Figure 5 is an explanatory diagram of sampled peripheral position data, and Figure 6 is linear interpolation processing. FIG. 7 is an explanatory diagram of the interpolation process for the orientation flat portion, and FIG. 8 is an explanatory diagram of the orientation flat end detection process. 1...Table 2...Pulse motor for driving wafer rotation 3...Light source 5...Pulse motor for light source displacement 6...CCD line sensor 9...CCD drive circuit 1O...Signal Processing circuit 11...A/D converter 12...CPU 13...RAM 14, 17...Pulse generation circuit 15...Pulse motor drive circuit 16...Counter 18...Pulse motor drive Circuit W...wafer

Claims (1)

[Claims] (1) A wafer peripheral exposure device that rotates a wafer coated with photoresist and exposes the periphery of the wafer with an exposure beam, the device comprising: wafer rotation drive means for rotationally driving the wafer; and the wafer rotation drive. a rotational drive control means for stepping the means at a predetermined angle; a light source for irradiating an exposure beam; a light source displacement means for relatively displacing the positional relationship between the light source and the wafer; a one-dimensional image sensor for detecting; a data capture timing control means for providing a timing for capturing peripheral position data from the one-dimensional image sensor when the step feeding is stopped; and a storage means for storing the captured peripheral position data; Light source displacement control means for controlling the amount of displacement of the light source displacement means based on the peripheral position data of the wafer stored in the storage means each time the wafer rotation drive means steps forward during exposure. Wafer peripheral area exposure equipment.