JPS5830128A - Waffer chuck device - Google Patents

Abstract

PURPOSE:To retain the substrate surface at a desired position with a high precision by means wherein three points are detected on the surface of the substrate on a chuck securely supported on three support studs, two of said support studs being moved up and down separately, whereby the relative height of the studs is controlled according to the levels of the substrate surface. CONSTITUTION:A substrate 2 is adhered to a chuck 1 and its surface has three points detected to give X-Y coordinates from which fine motion DELTAZ1 to DELTAZ3 of a fine adjustment mechanism 21 is obtained by a primary controller 25. In order to make the wafer surface 9 coincident with the image-forming surface 3 of the mask pattern, the deviation DELTAz should be coincident on the coordinates of the three fine adjustments 21. Assuming that fine adjustment 21 takes place when the fine motion DELTAZ1 to DELTAZ3 is fed to a piezo-controller 23, the substrate surface comes into coincidence with the pattern surface 3. This is repeated until the coincidence is attained or predetermined times. With this constitution, matching precision becomes less than + or -0.5mum and the substrate is free from damage because of non-contact operation, and quick operation is possible.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wafer chuck device for holding a plate material such as a wafer forming a semiconductor integrated circuit or the like with high precision fK.

Wafer chucks are often used in semiconductor devices and the like.

Figure 1 shows an example of use in a projection type liner.

1 is a wafer chuck, 2 is a wafer, 4 is a projection optical type, 5
is mask% 6 is slide table, 8 is 7 liner base. The wafer chuck 1 attracts the wafer 2t and fixes the wafer 2 in line with the convergence surface 5 of the mask I (turn).The conventional spherical seat type wafer chuck 1 has a high precision in this fixing. In other words, the alignment accuracy between the surface of the wafer 2 and the imaging plane 3 is 11 m1t' for 2 μl.However, when the width of the semiconductor integrated circuit collar is 5 μm to 2 μm, The following becomes n, # image plane 5 and surface 2 to ±
It became necessary to adjust the amount within 1 μl, so the single spherical seat method was used.
It has become necessary to have a cooling drip.

FIG. 2 shows a conventional spherical seat type wafer chuck. The conventional wafer chuck has a wafer chuck surface 10 that attracts the wafer 2, a vacuum conduit 11 for the chuck, a spherical seat 121, a vacuum conduit 15 for fixing the spherical seat, and an upper part of the wafer surface. sedato fL
It consists of a holding rod 14 and a wafer rig lowering mechanism 15.

Figure 5 shows the operation of the spherical eel stack type wafer chadag (
A) shows a state in which 19 wafer chucks 1 are lowered onto the vertical mechanism 15, 2 tons of wafers are placed on the wafer chucks, and the wafers are exposed to the vacuum knife 18 for wafer chucks. Here, the sea urchin genus 10 is tilted and is away from the mask pattern imaging plane 3. At this time, the vacuum 19 for the spherical seat is not working, and the wafer 2 is moved up and down by the vertical mechanism 15 of the 0th order lbl, which is the spherical seat j2Fi7, and the periphery of the wafer 2 is brought into contact with the abutting rod 14. The contact rods f4Fi are arranged at three points on the side of the curve, and the plane connecting the tips of the contact rods 14 is parallel to the mask pattern imaging plane 5 in advance. For this reason, if it is continued to be raised by the vertical mechanism 15, the predetermined pressure 17, and the predetermined pressure 17, it will stop when the wafer surface 9 becomes parallel to the mask pattern imaging surface 15 due to the single spherical seat S2. When the vertical mechanism 15 stops, move the spherical seat 1 as shown in (o).
21i - Apply the vacuum 19 for the spherical seat to fix it. Last K
As shown in (d), the wafer chuck 1 is
lower. The amount of lowering is the distance 16 between the tip of the abutting rod 14 and the mask pattern image forming surface 5, and the distance between the wafer surface 9 and the mask pattern image forming surface 5 is 0 or more.
This means that they match with an accuracy of ±2 Am 2 points.

The above operation is performed for each wafer. This is due to the back dP (±5μ-~ This is a method to correct the difference (±10μI).

The above L-type method has the following drawbacks.

As mentioned earlier, the first Fi is a point when the wafer surface 9 and the pattern imaging surface do not match. This has two problems: parallel alignment and height alignment. First, the parallel alignment of m is achieved by using the spherical seat 12 due to the rigidity of the true 9 conduit 11 for the wafer chuck.
The second reason is that the spherical seat 12 moves due to vacuum force when fixed, the third reason is that the reproducibility of the contact is fkTA, and the fourth reason is that the vertical mechanism 15 There are problems such as deflection due to lack of rigidity when pressurizing is applied during abutment.Height adjustment is not reproducible in the vertical mechanism 15, and the above-mentioned abutment is not reproducible.
There are problems such as compatibility due to improper rigidity when the pressurized tank is applied when the vertical mechanism 15 butts.

The second problem is that it comes into contact with the wafer surface 9. Kof
Is i the dirt on the tip of the abutting rod 14, or conversely the wafer surface? This may cause stains on the wafer A and damage to the wafer 82.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide a method for aligning eight sea urchin genera with a mask pattern surface with high precision.

That is, the present invention is to place a wafer chadag on the three points of the vibrator and slightly move the vibrator up and down to align it with the eight surfaces of the KL9 wafer. The fine vertical movement of the vivodator is performed by a piezo element, etc., and the wafer surface is detected for positioning of the wafer surface, and a feed pulse is applied to this nv vertical movement.

The present invention is illustrated below in 5j! This will be explained in detail based on examples.

41st OK Example 1 of the present invention is shown. , Piezo fine movement upper and lower 4# (hereinafter referred to as the fine movement mechanism 21) arranged on the base 20 at three places on the circumference, the entire circumference of which is supported by the fine movement mechanism 21. Based on the wafer chavuk 1 20
Spring that attracts 22. Vacuum pipe line 11 for wafer chuck
1 piezo control. -La 25. 9th place ft - 5 capacitance type detectors 24 arranged on the circumference to be detected and the fine movement rK of each fine movement mechanism 21 from the detectors 24
It consists of a main control σ-225 which calculates and moves the Viezo controller 25.

The operating procedure is as follows. First, the wafer is placed on a 2t wafer and adsorbed. The wafer surface 9 at this time is detected by the detector 24, and is designated as m, aKl, and Z@, respectively. Here, determine the X and Y coordinates as shown in Figure 4 and use the main controller 2.
5, the fine movement amount Δz of each fine movement mechanism 21, 8△z1. Δ2. seek. The calculation method is shown below. IF (X
,,Ylmg,), CX1. Y, avl).

(X,, Y, g,) Substitute into the f-plane general formula % formula % (1) to find each coefficient. The wafer surface is as shown in the following equation.

z, = A, X+B, Y+C, (2) On the other hand, it is assumed that the mask pattern imaging plane 3 is determined in advance as follows.

E @=A1 X+B@ Y+C@ (3) Therefore, if the difference between the wafer surface 9 and the pattern imaging surface 5 is Δ2, Δz−H−E, −(AM−A,)X+(Bll−B, )
Y+cH-CW(4) VC to match wafer surface 91t pattern 1 connection surface 5 is 3
It is sufficient if the coordinates of the two fine movement mechanisms 21 match.

Δ2 at each coordinate is the amount of fine movement of the fine movement mechanism 21.

That is, each fine movement mechanism 210 coordinate k (IC, I YC
,) a(x,,,Yal)-CXcs,Ych)
Then Δz1. ΔE1. Δz1 is found by substituting into (4) 2.

Δ! ! +-(Ar(w)XCH+(BrB,)Y)1→
C1l"'Cw, (5)bxH-(AH(,
)Xg 1+CB(B,)Y(1z+cH-C, (6)
tsz 4(k(k,) X6 %Bkl'-By)Y
C--(, (7) or higher value piezo controller 2sK
If the fine movement mechanism 21t is moved, the sea urchin convex surface 9 will match the pattern condensation surface 5. If there is a detection error or a slight movement error, the wafer surface 9 is detected again, and if they do not match, the above operation may be repeated for a certain b a predetermined number of times until they match.

It is not necessary for the fine movement mechanism to move in three places, and it may be possible to make fine movement in only two places individually. In this case, as in the fifth factor, a separate vertical movement mechanism 12 is required, but the structural rigidity for the chuck is 1. Ef is improved because the pillars in these places are (support) fixed. Also, in this case, the amount of microtremor is expressed as CM-C1's * in equation (4).
1- Vertical movement mechanism 12 adjusts, (All *w)x+<
sH-Bw) Y t-11 movement mechanism adjusts.

The detection of the wafer surface does not need to be a capacitance method; any method such as electric micro, ultrasonic sensor, optical sensor, air micro, etc. may be used as long as it does not affect the wafer posture during detection and does not adversely affect the process. You can fully scan one number,
Any number is fine, as long as it can detect the wafer surface at five points that are not on a straight line and determine whether it belongs to a sea urchin.

Instead of the piezo bulge, a Kff, a body-applied fine movement mechanism, a motor-based fine movement mechanism, etc. may be used.

The wafer surface can be determined using equation (1), but it is more accurate to calculate the average surface from data from four or more points.

FIG. 6 is a diagram showing another embodiment according to the present invention. Fourth
In addition to the figure, five leaf springs 40 are used to connect the bottom of the chuck and a leaf spring support ring 410 on the base 20 to improve the horizontal rigidity of the wafer. Changes in posture in the vertical direction are not sufficient because the leaf spring 40 has low vertical rigidity and low torsional rigidity around the horizontal axis. The arrangement fIL of the leaf spring 40 can be anywhere as long as the vertical stiffness and torsional stiffness around the horizontal axis are low and the horizontal stiffness is high so that the posture can be changed in the vertical direction.
1. Anything is fine, such as a steel material with a notch or a one-disc leaf spring.

If the present invention is implemented as explained above, the following effects can be obtained.

(1) The accuracy of matching the convex surface of the sea urchin and the makku pattern has been improved several times compared to the conventional method, and ±(L5Jfl or less, fine) (turn printing is possible).

(2) Wafer surface alignment can be performed without contacting the wafer surface.
The yield can be improved by one level without damaging the wafer.

(3) Operation becomes faster.

(4) The vertical mechanism and parallel alignment mechanism can be combined into one, making it more compact.

[Brief explanation of the drawing]

Figure 1 is a diagram showing an example of using a conventional wafer chavuku in a projection aligner. Figure 2 is a diagram showing the structure of a conventional wafer chavuku. FIG. 4(a) is a diagram showing the operation of the chadak, and FIG. 4(a) is a diagram showing an embodiment of the chadak device for sea urchins of the present invention. Fig. 4 (B is a view taken along the arrow A of Fig. 5(a), Fig. 5 is a diagram showing another embodiment different from Fig. 4, Fig. 6 (al
6 is a partial sectional view showing another embodiment 1 different from No. 45!5, and FIG. 1... Chuck to the sea urchin, ? -・To the sea urchin, 20・・
・Pace% 21 Motion mechanism, 22...Spring, 2B...
・Piezo controller, 24...Capacitance detector, 2
5... Main controller, Sa-...ti! 1 leg prop% 40...plate spring. Representative Patent Attorney Usuki 1) Li *(yj)C", -, -11 ke l 211!1 years old 4 Figure (L') Gu 5I!I Me Otsu Figure (') (b'>

Claims (1)

[Claims] 1. Support columns arranged at at least 5 points on a straight line on the pace and capable of placing the wafer chuck on at least 3 points, and supporting the wafer chuck horizontally. A fixing means for fixing to the supporting columns, a detecting means for detecting the position of the wafer on the wafer chuck at at least five locations not on one line, and a vertical mechanism for raising and lowering at least two of the supporting columns. , in order to create the desired shape of the eight sea urchin genera based on the position of the eight sea urchin genera detected by the detection means,
A wafer chucking device characterized by comprising: control means for fully controlling the relative heights of the five support struts, and for shaping the eight species of sea urchins on the sea urchin to a desired shape. λ The wafer apparatus according to claim 11, wherein the up-and-down mechanism is configured such that all of the support columns move up and down sideways. 5. The wafer chucking device as set forth in claim 1 or 2, wherein the up-and-down mechanism is comprised of a piezo element. The scope of claim 1 t is characterized in that the wafer chuck and the base are connected by a structural member that has low rigidity in the vertical fine movement direction and torsional rigidity around the horizontal axis, and 1 has high rigidity in the horizontal direction. is the chuck device for the hook described in item 2.