DE8112436U1 - Device for the automatic adjustment of flat objects with two reference points, in particular in the manufacture of semiconductor components - Google Patents

Description

In the manufacture of electrical semiconductors, structures that are located on copy masks and are similar to one another are created mapped onto each other and copied. It is essential- ^ • lent the mask and substrate (wafer) during the copying process are aligned with each other.

For example, US Pat. No. 4,211,489 discloses a device which operates with a laser known for the automatic adjustment of the photomask with respect to the wafer. The photo mask is used for the adjustment process and the wafer each have two reference marks, which are created by controlled relative movement between the photomask and the wafer are brought into register. The control signal required for this is derived in the following way. The laser beam from the laser is split into two parallel reference beams, whose spacing is equal to that of the reference marks on the photomask and the wafer. In the target position the two reference marks on the photomask and the wafer are in line and are in the beam path of the two parallel laser beams. Are the fiducial marks on the photomask and the wafer do not coincide and / or deviate from the beam path of the two light beam bundles, so are reflected from the Light control signals for the positioning of the photomask relative to the wafer are derived, so that you get the desired Target position received.

The object of the invention is to provide a simple and precise device for such an automatic adjusting device provide, with the help of which a pre-adjustment by hand, a check of the automatic adjustment and /

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or the target parameters for the automatic adjustment can be determined.

To solve this problem, the device according to the preamble of claim 1 has a so-called split field

Microscope, the two beam paths at least in the area of the reference markings on the photomask and the J 'wafer with the corresponding beam paths of the two light beam bundles can be brought to cover.

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The essence of the invention thus generally consists in a so-called splitfield microscope with an automatic one Combine adjusting device whose reference position is determined by two essentially parallel light beams is defined, the beam paths of the two light beam bundles with the suitable optical device associated two beam paths of the splitfield microscope be brought into congruence at least in the vicinity of the reference markings of the object to be adjusted. In this sense the device according to the invention is not based on the adjustment of wafers and photomasks described in more detail here limited in the manufacture of semiconductor components.

The device according to the invention is extremely compact and enables precise parameter specification and monitoring of the automatic adjustment. As special It is advantageous to consider that the same reference markings are used for viewing with the splitfield microscope can be used on the object to be adjusted as well as for the automatic adjustment process and thus positioning errors can be avoided in the two adjustment processes due to different reference points. Also is none Relative movement between the adjustment device and the object during the transition from adjustment with the Splitfield-35 Microscope required for automatic adjustment or vice versa, as the beam paths in the area of the reference mark

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- ο -ings on the object match in both cases; much more only the lens shoe of the microscope has to be inserted into the laser beam path (possibly with a simple positioning stop) or swiveled out of this. Positioning errors due to imprecise motion sequences between the two adjustment processes are thus avoided.

The distances between the beam paths of the two light beam bundles and / or of the split-field microscope are preferably I 10 adjustable, this adjusting process according to the invention I coupled, i.e. carried out together, so that when a

I. derlich becoming adjustment of the distance due to a |: Different spacing of the reference marks on the object

I. . by adjusting both the Splitfield-S 15 microscope and the light beam for the automatic adjustment are set to the new value together ■; will.

I Advantageous further developments can also be found in the

Ϊ 20 subclaims and from the description below '! "· Of an embodiment with reference to the drawing.

• · Show it:

• i Fig. 1 is a partially sectioned schematic front

i 25 view of the adjusting device according to the invention

; and

r Fig. 2 is a partially sectioned side view of the

; Device according to FIG. 1.

30 In the embodiment shown, it is on an object table 1, a substrate or wafer 2 is attached, over which a mask 3 is arranged plane-parallel. Both the mask 3 as well as the substrate 2 each have at least two reference markings 3a and 2a corresponding to one another

35 an edge length of a few tenths of a mm. Examples of such fiducial marks are described in U.S. Patent 4,211,489; for example, the two reference markings 2a

ii the substrate 2 the diagonally divided diffraction gratings

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on the wafer and the reference marks 3a of the mask 3 correspond to the two opaque alignment marks on the mask in the US-PS.

The automatic adjustment takes place with the help of a laser 4, whose suitably coZLinier.tes laser beam bundle 5 in a splitter prism 6 in two parallel (partial) light beams 7, 7 * is split up, which finally via deflecting prisms 8 and 8 'so parallel to each other be deflected so that they are approximately perpendicular to the mask 3

and wafer 2 existing combination hit. '|,

The splitter prism 6 and the two Abienkprisms 8 '1

"are on a prismatic lens 9 on which |.

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The two deflection |. prisms 8 or 8 ¹ (in the drawing) horizontally so displaced ;; ben can be that the distance between the two exiting light beams 7 and 7 'from each other is equal to the target distance between the reference markings 2a, 3a on the one hand

and 2a ¹ , 3a ¹ on the other hand.

For automatic adjustment, for example, the mask 3 can be shifted linearly in its plane (indicated by the double arrow.

is indicated) and / or about an axis 25 perpendicular thereto

to be turned around. This movement takes place with the help of an automatic control, not shown, such as in the U.S. Patent 4,211,489. For this purpose are in the housings for the deflecting prisms 8, 8 · concentric to the;

Light beams 7 and 7 ¹ each have a plurality of detectors 11 30

or 11 'arranged in a circle, with the output signals of which the movement of the mask 3 is controlled on the basis of the diffraction pattern generated ^{by the reference markings 2a, 3a or 2a 1} , 3a ^1. In addition, 3 diaphragms 12 or 12 'can be provided directly in front of the mask in order to collinate the beam path.

be seen.

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According to Pig. 2, a splitfield microscope 13 is arranged in front of the prism slide 9, which is attached to the housing 15 of the device with the aid of a bracket 14 Eyepiece 17 and the associated objective 18 is shown in phantom. At the exit end of the objective 18, an objective shoe 19 with two deflecting prisms 20, 21 is attached so that the beam path 16 between the deflecting prism 21 and the wafer 2 with the associated light beam 7 after the deflecting prism 8 can be brought into congruence. The same applies to the second beam path of the splitfield microscope 13, which can be made to coincide with the beam path ■ of the light beam 7 'after the deflecting prism 8' so that the relative position of mask 3 and wafer 2 can be determined with the aid of the splitfield microscope 13 to the beam path of the light beam 7 and 7 ¹ can check directly. '

During the automatic adjustment process InIt _{- with the} help of the light beam 7 and T from the laser 4, the objective shoe 19 is swiveled out of the beam path of the light beam 7, 7 ¹ , that is, the deflecting prism 21 is no longer in the beam path between the prism carriage and the mask. Wafer combination.

The adjustment of the two deflecting prisms 8 and 8 'in Prismatic slide using adjusting screws 10 or 10 * can be used directly with the adjusting device, not shown, for the distance between the two objectives of the splitfield microscope. 13 be coupled so that the adjustment to the spacing of the reference marks is only made once must become.

According to Figure 2, the laser 4 is arranged with a horizontal axis above the housing 15 in a laser house 22, and.

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the light beam emerging from the laser 4 is directed downwards into the splitter prism 6 via a deflecting prism 23 diverted. This arrangement results in a very compact structure.

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Summary:

Device for the automatic adjustment of flat objects with two reference points, especially during manufacture of semiconductor components.

The adjustment device enables the automatic positioning of a flat object with two reference points in For this purpose, two parallel light beam bundles with the two reference points are placed opposite a target position of the object brought into congruence, in_dem the reflection or the diffraction of the bundle of light rays on The object is measured by detectors and a control signal is derived from this in order to control the movement of the object to steer into the target position. For pre-adjustment, for A split-field microscope is provided for specifying parameters and / or for monitoring the automatic adjustment both beam paths at least in the area of the reference markings of the object with the two beam paths for the automatic adjustment can be made to coincide (Figure 2).

Claims (1)

Protection claims 1. Device for the automatic adjustment of at least one ^{flat object (2; 3) having two reference points (2a, 2a 1} J 3a, 3a ¹ ) with respect to a reference position defined by two essentially parallel light beams (7, 7 '), the reference points (2a * 2a ¹ ; ^ a, 3a ¹ ) by controlled transverse displacement of the object (2; 3) or the objects (2, 3) that can be moved relative to one another with respect to the light beam bundles (7, 7 ') are brought into congruence with their beam path , in particular for the production of semiconductor components, characterized by a split-field microscope (13) and an adjusting device (10, 10 ') for the beam paths (16, 16') of the microscope relative to the beam path of the two light beams (7, 7 ¹ ). 2. Device according to claim 1, characterized in that the beam paths of the two light beams (7, 7 ') and the beam paths (16, 16') of the SpI ' et ield microscope (13) perpendicular to the plane of the object (2; 3 ) or the levels of the objects (2, 3) are arranged. 3. Apparatus according to claim 1 or 2, characterized in that the distance between the beam paths of the two Light beam (7, 7 ') is adjustable. 4. Device according to one of claims 1 to 3, characterized by one in the beam path of the laser beam (5) arranged beam splitter (6). 5. Apparatus according to claim 4, characterized by a splitter prism (6) which splits the laser beam (5), 6. Apparatus according to claim 4 or 5, characterized in that the split laser beam is ^{deflected by two deflecting prisms (8 or 8 1} ) in mutually parallel light beam bundles (7, 7 '). 7. Apparatus according to claim 6, characterized; shows that the optical distance between the two deflection prisms i men {8, 8 ') is adjustable =; 3. Device according to one of claims 3 to 7, characterized in that; characterized in that the distance between the beam paths of the two i the light beam (7, 7 ') and the distance between the two j Beam paths of the split-field microscope (13) together is adjustable. j J9. Device according to one of Claims 1 to 8, characterized through one into the beam paths of the two Light beam (7, 7 ') pivotable lens shoe (19) on the objectives (18) of the splitfield microscope (13). 10. Apparatus according to claim 9, characterized in that 35 β «· Il ti ·· · {ti · · ~ l 20th 25th 30th 35 that the lens shoe (19) has two prisms (20, 21) for each beam path for parallel offset of the beam path of the splitfield microscope (Ij5) into the beam path the light beam (7 or 7 ').