JPS63141313A - Thin plate deformation device - 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 thin plate deformation for flattening the surface of a thin plate sample such as a semiconductor wafer into a desired shape. The present invention relates to a thin plate deforming device suitable for correction.

[Prior Art] As described in Japanese Patent Publication No. 57-23418, a conventional thin plate deforming device has a plurality of vertical drive devices arranged below a thin plate sample such as a semiconductor wafer, and is used to reduce irregularities on the surface of the thin plate sample. Based on the measurement results, one surface of the thin plate sample is brought into a desired state by partially moving it up and down using the vertical drive device.

[Problems to be Solved by the Invention] In the above-mentioned prior art, the range in which the surface shape of the thin plate sample can be changed is determined by the interval between the parts that are moved up and down, and the minimum interval is limited by the size of the vertical drive device. Therefore,
Even if the part that can be moved up and down can be made into a desired shape, the part that cannot be moved up and down between them changes depending on the elastic modulus of the thin plate sample.

Techniques for accurately flattening a thin plate sample into a desired shape, for example, will become increasingly important in the future. For example, with the miniaturization of semiconductor integrated circuits in recent years, when transferring a circuit pattern formed on a mask, it is necessary to make the gap between the mask and the wafer with semiconductor uniform on the order of several microns, and to reduce the uniformity to 1 micron or less. is occurring. However, in the above-mentioned conventional technology, the size of the unevenness that can be corrected is limited depending on the size of the vertical drive device as described above, so it is difficult to cope with future miniaturization of semiconductor devices and the like.

An object of the present invention is to provide a thin plate deforming device that easily deforms the surface of a thin plate sample so that the gap between the mask and the thin plate can be made uniform to 1 micron or less.

[Means for solving the problem] The above purpose is to provide a planar electrostrictive element integrally at the bottom of a planar sample adsorption section, and to install a large number of linear electrodes in parallel on each of both sides of the electrostrictive element. , and the linear electrodes between both sides intersect.

achieved.

[Function] If the surface of the thin plate sample adsorbed by the sample adsorption section has unevenness, when an electric field is generated between the linear electrodes on both sides of the electrostrictive element whose intersection point is at the point, the corresponding point of the electrostrictive element will be distorted. . This distortion is transmitted through the sample adsorption section, and the distortion of the thin plate sample is canceled out, so that the thin plate sample becomes flat.

By narrowing the spacing between the linear electrodes, accuracy can be improved. In addition, using multiple electrostrictive elements,
The linear electrodes of another electrostrictive element may be arranged between the linear electrodes of one electrostrictive element, so that the linear electrodes are lined up at minute intervals when viewed as a whole.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is an overall configuration diagram of a thin plate deforming device and a control system according to an embodiment of the present invention. The thin plate deforming device 1 of the embodiment shown in FIG.
It consists of four electrostrictive elements 4 that are integrally provided at the lower part of the wafer suction section 3. This thin plate deforming device 1 is placed on an XY table 6 placed on a base 5, and the surface of the wafer 2 is measured by a measuring means consisting of a non-contact sensor 7. The output of the sensor 7 is amplified by an amplifier 8 and then sent to an A/D converter 9.
The signal is converted into a digital signal and given to CPU10. On the other hand, although not shown, the shape of the surface of the mask facing the wafer 2 is also measured by measuring means consisting of a non-contact sensor. This measures the gap between the mask and the wafer. Based on this gap input signal, the CPU 10 outputs a control signal to the electrostrictive element driver 11 so as to indicate a constant value, and corrects the unevenness of the wafer 2, as will be described in detail later. Further, the CPU 10 outputs a control signal to the control circuit 12 of the motor 13 that drives the XY table 6.

FIG. 2 is a top view of the wafer suction section 3. The wafer suction part 3 is made of a square plate, and the central part 3a is circular and planarly protruded. This central portion 3a is formed to have a slightly larger diameter than the wafer 2, and countless narrow grooves 3b are carved on the inside (Fig. 2 shows the grooves 3b with a larger width). The multi-grooves 3b are carved so as to communicate with each other, and the outer peripheral part 3c of the central part 3a is a protruding ring on which the peripheral part of the wafer 2 is placed. As for wafer 2.

It is sucked and supported in a plane by countless support protrusions 3d formed between the protruding ring 3c and the groove 3b.

At the bottom of the groove 3b is a passage 3e (pierced inside the wafer adsorption section 3) that is connected to a vacuum pump (not shown).

An opening 3f shown in FIG. 1) is provided.

FIG. 3 is a perspective view of the electrostrictive element 4. The flat electrostrictive element 4 is made of a material that has an electrostrictive (anisotropic displacement due to electric polarization in a ferroelectric material) effect, and has a square shape with the same size as the wafer adsorption section 3 . On the upper surface of the electrostrictive element 4, a large number of linear electrodes 4a are formed equally spaced and parallel to each other by, for example, vapor deposition. A large number of linear electrodes 4 are also provided on the lower surface of the electrostrictive element 4.
b are formed equally spaced and parallel. This linear electrode 4
b is arranged so as to intersect with the linear electrode 4a on the upper surface, or at right angles in this embodiment.

Both surfaces of the electrostrictive element 4 are coated with an insulating film to protect the electrodes 4a and 4b and to prevent short circuits. Each of the electrodes 4a, 4b is pulled out to the outside and connected to the electrostrictive element driver 11 (FIG. 1), and the arbitrary electrodes 4a, 4b are
A DC electric field is applied between b.

FIG. 4 is an electrical configuration diagram of the electrostrictive element 4. Figure 4 (a
), a capacitance is formed between the top electrode and the bottom electrode of the electrostrictive element, and when charge is supplied to this capacitance,
Due to the electrostrictive effect, the electrostrictive element changes its thickness. For example, A
If you want to change the thickness at a point, if you apply a DC electric field between the top ffi pole B and the bottom electrode C that intersect at the point A, the thickness at point A will change as shown in Figure 4(b). changes.

Therefore, when a thin plate deforming device equipped with such an electrostrictive element is fixed on a reference surface and the thickness of a desired portion of the electrostrictive element is changed, the change is applied to the wafer through the wafer suction part integrally joined to the upper part. It is possible to correct the unevenness of the wafer. This is because such a change occurs on the micron order, so that the wafer suction part, wafer, or upper electrostrictive element of a multilayer structure, which is hard from a macroscopic perspective, can be considered to be soft from a microscopic perspective.

The electrostrictive element 4 has the configuration shown in FIG. 3, and as can be easily inferred from the above, there are
The narrower the interval between the two, the more accurate unevenness correction can be obtained. However, if there are manufacturing difficulties, a plurality of electrostrictive elements may be stacked and used as in this embodiment. For example, if the electrode spacing of one electrostrictive element is 8 microns,
By stacking four electrostrictive elements with a shift of 2 microns each, an electrostrictive element having electrodes substantially spaced apart by 2 microns can be obtained.

A method of equalizing the gap between the mask and the wafer, that is, increasing the flatness of the wafer using the thin plate deforming device having such a configuration will be described.

When transferring a circuit pattern onto the wafer 2 using the xNIAn light method or the excimer laser exposure method, first place the wafer 2 on the suction section 3, and evacuate the groove 3b of the suction section 3 to uniformly spread the entire surface of the wafer 2. Hold it by adsorption. And the CPU
The XY daple 6 is moved back and forth and left and right according to instructions from l0, the uneven state of the entire surface of the wafer 2 is detected by the sensor 7, the surface of the mask is measured, and the gap between the mask and the wafer 2 is stored in the memory in the CPU 10.

Next, the CPU10 selects the upper surface electrode 4a and the lower surface electrode 4b according to the gap between the mask and the wafer 2, and sets the required polarity and required size between the selected electrodes according to the gap and its size at the relevant location. Driver 1 so as to apply a DC electric field of
A control signal is output to 1.

As a result, the thickness of the electrostrictive element 4 at a required location changes, the unevenness of the wafer 2 is corrected by the change in the electrostrictive element 4, and the gap between the mask and the wafer 2 is made uniform.

By transferring the circuit pattern on the mask to the wafer in this state, a fine pattern is clearly drawn on the wafer 2. At this time, since the capacitance of the electrostrictive element is not an ideal capacitance, charge leakage occurs. On the other hand, by repeatedly supplying the lost charge, the charge at each point can be maintained at a substantially constant value. Thereby, the change in the electrostrictive element, that is, the flatness of the wafer 2 is similarly maintained.

According to this embodiment, it is possible to sufficiently achieve the flatness required in the highly integrated semiconductor manufacturing process (in particular, the X-ray exposure method used in lithography of 0.5 μm or less),
This has the effect of making mass production possible.

It goes without saying that the present invention is not limited to the flattening of semiconductor wafers as in the above-mentioned embodiments, but can be effectively applied to other technical fields where it is necessary to create highly accurate flat surfaces.

[Effects of the Invention] According to the present invention, there is an effect that the surface of a thin plate sample can be made into a highly accurate flat surface on the order of submicrons.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a thin plate deforming device and a control system according to an embodiment of the present invention, Fig. 2 is a top view of a wafer adsorption section, Fig. 3 is a perspective view of an electrostrictive element, and Fig. 4 (a). is an electrical configuration diagram of the electrostrictive element, and FIG. 4(b) is an explanatory diagram of changes in the electrostrictive element. DESCRIPTION OF SYMBOLS 1... Thin plate deformation device, 2... Wafer, 3... Wafer adsorption part, 4... Electrostrictive element, 4a, 4b... Linear electrode, 11... Electrostrictive element driver. Agent Patent Attorney Tadashi Akimoto Figure 1 Figure 2 Figure 3 Figure 4α b s4 Figure (Q) (b)

Claims (1)

[Claims] 1. Forming a large number of linear electrodes in parallel and at equal intervals on the top surface,
A planar electrostrictive element, in which a large number of linear electrodes are formed on the lower surface in parallel and equally spaced at angles that intersect with these linear electrodes, is integrated into the lower part of a flat adsorption section that adsorbs and holds the thin plate sample to be deformed. A required electric field is applied between the upper surface linear electrode and the lower surface linear electrode that intersect at the uneven portion of the thin plate sample, and the thickness of the electrostrictive element at the corresponding portion is changed to change the thickness of the thin plate sample. A thin plate deforming device designed to offset unevenness.