JPH0569306B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a wafer chuck used in an exposure apparatus for exposing fine patterns on thin plates such as semiconductor wafers and bubble memory wafers, and particularly suitable for flattening the wafer surface. This invention relates to a wafer chuck, that is, a thin plate flattening chuck.

[Background of the invention]

The wafer chuck in conventional exposure equipment is as described in Japanese Patent Application Laid-open No. 106118/1982
The piezo element that deforms the wafer and the wafer suction thin plate are brought into contact with each other under vacuum pressure, and the piezo element is expanded and contracted to partially deform the wafer suctioned to the wafer suction thin plate.

However, in the above-mentioned Muehachi chuck, in order to flatten the entire surface of the wafer, it is necessary not only to increase the arrangement density of the piezo elements, but also to make the structure and control complicated, and the cost to be high.

[Object of the Invention] An object of the present invention is to solve the above-mentioned problems and provide a flattening chuck for flattening thin plates (wafers) that can flatten the surface of thin plates (wafers) that have warps and undulations (thickness unevenness). It is.

[Summary of the invention]

In order to achieve the above object, the present invention provides a thin plate flattening chuck that flattens a thin plate (wafer) that has been vacuum-suctioned by deforming the thin plate in both upward and downward directions from the suction surface side of the thin plate. The thin plate flattening chuck includes a chuck plate provided with a vacuum adsorption surface on the front surface and a mesh-like slit groove on the back surface, and each intersection of the slit grooves is moved up and down,
It is characterized by comprising a plurality of vertically moving elements for deforming the thin plate, and a housing for vacuum suctioning both the vertically moving elements and the chuck plate.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a partially cutaway plan view of this embodiment, and FIG. 2 is a sectional view taken along line AA in FIG.

In FIGS. 1 and 2, a plurality of thin plate flattening chucks, for example, wafer flattening chucks 1, are attached to a chuck plate 2 that vacuum-chucks the wafer 6 to the front surface 2A, and a back surface 2B of the chuck plate 2. It consists of a vertically moving element 3 and a housing 4 for vacuum suctioning both the vertically moving element 3 and the chuck plate 2, and on the back surface 2B of the chuck plate 2,
As shown by two-dot chain lines in FIG. 1, a large number of slit grooves 5 are provided to form a mesh shape, for example, a large number of triangular lattices 7. Each triangular lattice 7 is independently moved up and down by the up and down movement elements 3 provided at each intersection of each slit groove 5. Furthermore, the chuck plate 2 and the vertical movement element 3 are joined to each other by vacuum suctioning the inside of the housing 4 via a vacuum source 10 attached to the housing 4.

The chuck plate 2 is made of aluminum, silicon, stainless steel, phosphor bronze, or the like in a plate shape, and has a land portion 8 and a vacuum suction port 9 for sucking the wafer 6 on its surface.

The vertical movement element 3 needs to have a stroke sufficient to flatten the wafer 6.
The warpage and waviness (thickness unevenness) of the wafer 6 are
Since it is 10 to 20 μm or less, a stroke of the vertically moving element 3 of 20 to 50 μm is sufficient. As the vertically moving element 3, a piezo element that expands and contracts depending on an applied voltage is most suitable.

The piezo element used is one that can obtain a large stroke, for example, a stroke of 20 μm/200 V in 100 layers, by stacking a plurality of plate-shaped piezo elements and applying a voltage to each element in parallel.

In addition, if a stacked piezo element is used that uses thick-film ceramic firing technology to alternately print electrodes on a green sheet of piezo material and then laminate them and then fire them together, the size and cost can be reduced. can be measured.

Next, an example of use of this embodiment having the above-mentioned configuration, that is, a case where a wafer is flattened, will be explained with reference to FIGS. 3 and 4.

First, as shown in FIG.
When the wafer 6 is fixed to the chuck plate 2, the warpage is eliminated by vacuum suction of the wafer 6 to the chuck plate 2, but the waviness remains. Therefore, the flatness of the surface of the wafer 6 is as shown in FIG. 3, and the flatness is measured by the measuring device 20. The measuring device 20
As a method, a well-known laser interference method or a flatness measuring device using a capacitance type sensor is used.

From the measurement results of the wafer flatness measured by the measuring device 20, each vertically moving element (piezo element) 3
A computer 21 calculates the amount of expansion and contraction, and a piezo driver 22 is connected to the computer 21.
A voltage is applied to each vertically movable element 3 to operate each vertically movable element 3, thereby flattening the surface of the wafer 6. This state is as shown in FIG.

By the method described above, the resolution of the piezo element 3 is
By controlling the fine movement to less than 0.02 μm and deforming the chuck plate 2, it is possible to flatten the wafer 6 within ±0.5 μm.

On the other hand, in this embodiment, as shown in FIG. 1, by using the triangular lattice 7 as a block and deforming the chuck plate 2 approximately into a fold line with the slit grooves 5 as boundaries, the entire surface of the wafer 6 is The arrangement density of the vertically moving elements 3 may be low in order to flatten the structure. For example, in the case of a 5″φ chuck plate, the grid pitch P
(See Figure 1) is 25 mm, and the number of vertically moving elements 3 is 36.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to flatten a wafer (thin plate) to within ±0.5 μm, so that warpage and waviness (unevenness in thickness) of the wafer can be eliminated. . Therefore, highly accurate pattern formation is possible in a semiconductor exposure apparatus for forming fine patterns.

Furthermore, since the gap between the mask and the wafer can be kept uniform in the X-ray exposure apparatus, pattern exposure with high resolution is possible.

Furthermore, since it is possible to deform the wafer approximately to a fold line, it is possible to reduce the arrangement density of the vertically moving elements, making it possible to reduce the size, weight, and manufacturing cost of the flat chuck. It is possible to measure it.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway plan view showing an embodiment of the thin plate flattening chuck of the present invention, and FIG.
A sectional view, FIGS. 3 and 4 are sectional views illustrating usage examples of the embodiment according to the present invention. 1... thin plate flattening chuck, 2... chuck,
2A...Front surface, 2B...Back surface, 3...Vertical movement element, 4...Housing, 5...Slit groove, 6...
...Thin plate (wafer).

Claims (1)

[Claims] 1 In a thin plate flattening chuck that flattens a thin plate by deforming the thin plate vacuum-suctioned in both upward and downward directions from the suction surface side of the thin plate, the thin plate flattening chuck applies vacuum suction to the surface. A chuck plate having mesh-like slit grooves on its back surface, a plurality of vertically moving elements that deform the thin plate by vertically moving each intersection of the slit grooves, and the vertically moving elements and the chuck plate. A thin plate flattening chuck comprising: a housing for vacuum suction;