Layout of a holding device for use in a piezoelectric substrate implantation process

Abstract

The invention relates to a holding device arrangement for use in a piezoelectric substrate implantation process (120), comprising a substrate holding device (110) having an elastic and thermally conductive layer (150) for receiving a piezoelectric substrate (120), characterized in that it further comprises means (160) for electrically connecting the surface of the elastic and thermally conductive layer (150) to receive the piezoelectric substrate at a ground potential (170). The invention also relates to a method for implanting a piezoelectric substrate using a holding device arrangement as described above, and an ion implantation device comprising such a holding device arrangement. Figure for the abstract: Figure 1

Description

Title of the invention: Holding device arrangement for use in a piezoelectric substrate implantation process

[0001] The invention relates to a holding device arrangement for use in a piezoelectric substrate implantation process, and a method for implanting a piezoelectric substrate using such a holding device arrangement.

[0002] The ion implantation process is used for piezoelectric fabrication to fabricate piezoelectric substrates on insulators (10). In a POI fabrication process, a thin piezoelectric layer is detached from a piezoelectric source substrate at the level of a weakened layer inside the source substrate formed by the atomic species implanted inside the source substrate, and transferred onto a manipulation substrate.

[0003] During implantation, the piezoelectric substrate is mounted on a metallic holding device inside an implantation chamber, and an implantation beam strikes a surface of the piezoelectric substrate. To implant an atomic species over its entire surface, the substrates are mounted on a rotating and / or translationally moving implantation wheel, such that the entire surface of the substrate passes under the ion beam. Holding means, such as clamps, are used to fix the substrate to the implantation wheel against the rotational forces. Typically, the holding means are fixed metallic retaining elements that are also configured to drain electrical charges generated during ion implantation.

[0004] The implantation of atomic species in the piezoelectric substrate results in an accumulation of charges. Simultaneously, a high temperature gradient is observed within the piezoelectric substrate, leading to deformation in the form of a basin and warping of the piezoelectric substrate. Consequently, charges and heat cannot be sufficiently dissipated in a metallic holding device.

[0005] To remedy this problem, the piezoelectric substrate is placed on a layer of elastomer provided above the metallic retaining device. This elastomer layer provides thermal contact between the piezoelectric substrate and the retaining device. As mentioned, the fixed metallic retaining elements are used to provide electrical contact between the piezoelectric substrate and the retaining device. However, the electrical contact is only a contact punctual between the piezoelectric substrate and the holding device, and a break in the piezoelectric substrate during implantation is always observed, which is attributed to a consistently insufficient discharge of charges.

[0006] Therefore, the dissipation of charges outside a piezoelectric substrate must be further improved.

[0007] The object of the invention is achieved by a holding device arrangement for use in a piezoelectric substrate implantation process, comprising a holding device with an elastic and thermally conductive layer for receiving a piezoelectric substrate, characterized in that it further comprises means for electrically connecting the surface of the elastic and thermally conductive layer for receiving the piezoelectric substrate to a ground potential. Thus, an electrical connection between the piezoelectric substrate and the substrate holding device can be established. This electrical connection provides improved charge dissipation through the elastic and thermally conductive layer, since dissipation does not occur solely through contact between the metallic holding elements and the piezoelectric substrate as in the prior art.

[0008] According to one embodiment of the invention, the elastic and thermally conductive layer can provide an electrical connection between the substrate holding device and the piezoelectric substrate over more than 30% of the back surface of the piezoelectric substrate, in particular more than 50% of the back surface of the piezoelectric substrate. Thus, a larger contact area is provided, improving the electrical connection between the piezoelectric substrate and the substrate holding device.

[0009] According to one embodiment of the invention, the elastic and thermally conductive layer may comprise a polymer layer, in particular an elastomer layer. Due to its elasticity, the polymer layer can compensate for deformations of the substrate, so that the substrate remains in constant thermal contact with the polymer layer and thus with the substrate support device. For example, a polydimethylsiloxane polymer layer having a thermal conductivity of 0.15 W / (m*K) may be used.

[0010] According to a variant of the present invention, the means for electrical connection may comprise at least one electrically conductive element integrated into the elastic and thermally conductive layer, in particular the polymer layer, in order to render the elastic and thermally conductive layer, in particular the polymer layer, electrically conductive. By integrating the electrically conductive element, the electrical conductivity of the layer can be improved in a simple yet reliable manner.

[0011] According to one embodiment of the invention, the at least one electrically conductive element may be at least one of metallic nanoparticles or metallic microparticles Talcic inclusions, carbon-based inclusions, graphite nanoparticles, or carbon nanotubes. These elements can be introduced into the polymer during its manufacture.

[0012] According to a variant of the present invention, the means for electrical connection may comprise at least one metal pin extending through the elastic and thermally conductive layer to the substrate holding device. It is particularly advantageous to provide a plurality of metal pins extending over the entire surface above which charges can be discharged.

[0013] According to one embodiment of the invention, each of the at least one metal pin can bear against a spring element provided in the substrate holding device. Thus, even under substrate deformation, the pins can remain in contact with the substrate. Furthermore, the restoring forces of the spring elements ensure reliable contact.

[0014] According to one embodiment, the metal pins protrude at least partially beyond the surface of the elastic and thermally conductive layer when no substrate is present. Thus, electrical contact can be guaranteed, even taking into account manufacturing tolerances.

[0015] According to one embodiment of the invention, the means for electrical connection may comprise a conductive layer, in particular a metallic layer, provided above the elastic and thermally conductive layer and extending laterally at least partially over the lateral surface of the elastic and thermally conductive layer to be in direct contact with the surface of the substrate holding device. The conductive layer provides reliable electrical contact with the piezoelectric substrate and the substrate holding device, and may be produced using known procedures, for example, sputtering.

[0016] The object of the invention is also achieved by a method for implanting a piezoelectric substrate, in particular a bulk piezoelectric substrate, using a holding device arrangement as described above, comprising the steps of a) providing a piezoelectric substrate onto the holding device arrangement to thus electrically connect the piezoelectric substrate to a ground potential and b) implanting atomic species into the piezoelectric substrate. The use of a substrate holding device as described above results in improved charge dissipation at the piezoelectric substrate, which in turn results in less breakage of the piezoelectric substrates during ion implantation.

[0017] The piezoelectric substrate that has undergone ion implantation can be used as a donor substrate in a subsequent layer transfer process to transfer a thin layer of the piezoelectric material onto a substrate of pulation, for example a silicon wafer, to form a piezoelectric substrate on an insulator.

[0018] The object of the invention is also achieved using an ion implantation device comprising a device retention arrangement as described above.

[0019] The present invention can be better understood by referring to the following description made with reference to the accompanying drawings, on which the numerical references identify the features of the invention.

[0020] Fig. 1 schematically illustrates a holding device for use in an implantation process according to a first embodiment of the invention.

[0021] Figure 2a schematically illustrates a retaining device for use in an implantation process according to a second embodiment of the invention.

[0022] Fig. 2b illustrates a variant of the second embodiment.

[0023] Figure 3 schematically illustrates a retaining device for use in an implantation process according to a third embodiment of the invention.

[0024] Figure 4 schematically illustrates a method for implanting a piezo substrate. electric according to a fourth embodiment of the invention.

[0025] Fig. 1 schematically represents a holding device arrangement 100 to be used in an ion implantation device (not shown) for a piezoelectric substrate implantation process according to the first embodiment of the invention.

[0026] The holding device arrangement 100 includes a substrate holding device 110 for holding at least one substrate 120 in a process chamber of an implantation device. The substrate holding device 110 is part of, or is positioned on, an implantation wheel of the implantation device. The implantation wheel rotates to move the substrates 120 through an ion beam 140, thereby achieving homogeneous ion implantation in the substrate 120.

[0027] The substrate holding device 110 is made of a conductive material, in particular a metal, for example aluminum. The substrate holding device 110 includes one or more metallic retaining elements 130 on a lateral side of the substrate holding device 110. In this embodiment, the substrate holding device 110 and the one or more metallic retaining elements 130 are made of the same conductive material, for example the same metallic material, in particular aluminum. The one or more retaining elements 130 hold the substrate 120 in place on the substrate holding device 110, for example when the holding device arrangement 100 rotates under an ion beam 140.

[0028] The substrate holding device 100 arrangement further includes an elastic and thermally conductive layer 150, which is positioned on a surface 112 of the substrate holding device 110. The elastic and thermally conductive layer 150 comprises a polymer layer 150, in particular an elastomer layer, to provide improved thermal contact between the substrate 120 and the substrate holding device 110. The elastic properties of the elastic and thermally conductive layer 150 compensate for the deformation of the substrate 120 under stress arising from the accumulation of charges and the temperature gradient within the substrate 120, and ensure thermal contact between the substrate 120 and the substrate holding device 110. The elastic and thermally conductive layer 150 can be applied as a coating by centrifugation or deposited onto the substrate holding device 110 using various deposition techniques.For example, a polydimethylsiloxane polymer layer with a thermal conductivity of 0.15 W / (m*K) can be used.

[0029] According to the invention, the elastic and thermally conductive layer 150 further includes means 160 for electrically connecting the surface 152 of the elastic and thermally conductive layer 150 which receives the substrate 120 to the substrate holding device 110 located below which is connected to the ground potential 170.

[0030] In this embodiment, the means 160 for electrical connection comprise at least one electrically conductive element in the form of electrically conductive elements 162 that are integrated into the polymer layer 150 to make the polymer layer electrically conductive. This can be achieved by adding metallic nanoparticles or microparticles, or carbon-based inclusions, graphite nanoparticles, or carbon nanotubes to the polymer layer 150. For example, the particles are mixed within the liquid polymer matrix. The solution is then deposited onto the substrate-holding device using a deposition technique such as spin coating. Subsequently, the polymerization of the elastomer is activated by UV curing and / or heat treatment.By doing so, the electrical conductivity of the elastic and thermally conductive layer 150 can be increased from 10 S / cm to the order of 104 S / cm.

[0031] During the implantation process, the ions 180 implanted in the piezoelectric substrate 120 can be discharged to the substrate retainer 110 via the polymer layer 150. The contact area between the substrate 120 and the polymer layer 150 is larger, compared to the contact between the substrate 120 and the fixed retainer 130 in the prior art, when electrically insulating polymer layers are used. Thus, charge discharge is improved, and less breakage of the piezoelectric substrate occurs during the step of implantation.

[0032] Indeed, according to the invention, the electrical connection can be provided over the entire surface of the polymer layer 150, which represents at least 30%, in particular at least 50% and more particularly the entire surface 122 of the substrate 120 which is in support of the polymer layer 150.

[0033] Figures 2a and 2b illustrate a holding device arrangement 200 according to a second embodiment. All features common to the first embodiment and using the same numerical reference as above will not be described again, but reference will be made to their detailed description above.

[0034] In the second embodiment shown in [Fig.2a], a plurality of metal pins 260 are provided in through-pairing holes 262 made in the elastic and thermally conductive layer 150 instead of integrated particles 162. The metal pins 262 extend through the elastic and thermally conductive layer 150 to the substrate holding device 110, which is in contact with the ground potential 170.

[0035] In this embodiment, each of the metal pins 262 bears against a spring element 264 provided in the substrate retainer 110. The metal pins 262 and the spring element 264 are designed such that, without a substrate present on the retainer arrangement 200, the metal pins 262 extend beyond the surface 152 of the elastic and thermally conductive layer 150. When a substrate 120 presses against the elastic and thermally conductive layer 150, the spring elements 264 are compressed, and the restoring forces of the spring elements push the metal pins 262 against the rear side 122 of the substrate. Thus, electrical contact with the rear side 122 of the substrate 120 is ensured, and charge drainage 180 into the substrate retainer is guaranteed. At the same time, the metal pins can follow any deformation of the substrate 120 under the ion beam.

[0036] According to one variant, as illustrated in [Fig.2b], the pins 252 may include an enlarged head portion 266 at their terminal end facing the substrate 120, so that the contact area can be enlarged even further.

[0037] Thus, as in the first embodiment, improved discharge of charges from the substrate 120 can be achieved. Charges can also be discharged via contact with the fixed metallic retaining element 130.

[0038] Figure 3 illustrates a holding device arrangement 300 according to a third embodiment of the invention. All features common to the first embodiment and using the same reference numeral will not be described in Figure 3. new, but reference will be made to their detailed description above.

[0039] In the third embodiment, the means for electrically connecting 360 are an electrically conductive layer 362 provided above the elastic and thermally conductive layer 150. In this embodiment, the electrically conductive layer 362 is a metallic layer, for example, an aluminum layer. It is deposited on the elastic and thermally conductive layer 150 using deposition techniques known in the art, for example, sputtering. The thickness of the electrically conductive layer 362 is on the order of 200 µm. The electrically conductive layer 362 is deposited such that it extends at least partially over the lateral edge 154 of the elastic and thermally conductive layer 150 to reach the substrate holding device 110. Thus, electrical contact with the substrate holding device 110 can be achieved.

[0040] Thus, in this embodiment as well, direct electrical contact is provided between the electrically conductive layer 362 and the substrate retaining device 110. Consequently, the discharge of charges 180 from the substrate 120 can take place over a large area on the rear side 122 of the substrate 120 in the electrically conductive layer 360 and from there to the substrate retaining device 110 at a ground potential 170. Again, charges can also be discharged via contact with the fixed metallic retaining element 130.

[0041] Figure 4 schematically illustrates a method for implanting a piezoelectric substrate according to a fourth embodiment of the invention. All features common to the first embodiment and using the same numerical reference as above will not be described again, but reference will be made to their detailed description above.

[0042] The method for implanting a piezoelectric substrate uses an arrangement of piezoelectric substrate holding devices 100, 200 and 300 according to any one of embodiments one to three as described above.

[0043] During step a), a piezoelectric substrate 120, in particular a massive piezoelectric wafer, is provided on the substrate holding device arrangement 100, 200, 300.

[0044] During step b), ions 140, for example hydrogen or noble gas ions, are implanted in the substrate 120. The ions 140 can be implanted in such a way that a mechanically weakened layer 142 is formed inside the substrate 120.

[0045] During implantation, a charge dissipation 180 occurs from the substrate 120 being implanted in the substrate holding device 110 via the electrical connection means 160, 260 or 360. The charge dissipation of the implanted piezoelectric substrate 120 is thus improved compared to an implantation process of the prior technique where the evacuation of charges 190 would take place only via the fixed retaining element 130 of the substrate retaining device 110.

[0046] The piezoelectric substrate 120 having undergone ion implantation can be used as a donor substrate in a subsequent layer transfer process to transfer a thin layer of the piezoelectric material onto a manipulation substrate in order to form a piezoelectric substrate on an insulator.

[0047] In such a process, the ion-implanted electrical substrate 120 is fixed, for example by bonding, onto a handling substrate, for example a silicon wafer, with or without an additional layer on the surface where the bonding takes place. The transfer of the piezoelectric layer then occurs at the level of the mechanically weakened layer inside the piezoelectric substrate 120 by applying a thermal or mechanical load.

[0048] Several embodiments of the present invention have been described. However, it should be understood that various modifications and improvements can be made, for example by combining one or more features of the various embodiments.

Claims

Demands

1. A holding device arrangement (100, 200, 300, 400) for a piezoelectric substrate implantation process, comprising a substrate holding device (110) having an elastic and thermally conductive polymer layer (150) for receiving a piezoelectric substrate (120), the surface of which is in contact with the entire elastic and thermally conductive polymer layer (150), characterized in that it further comprises means (160, 260, 360) for electrically connecting the entire surface of the elastic and thermally conductive polymer layer (150) to receive the piezoelectric substrate (120) at a ground potential.

2. A retaining device arrangement according to claim 1, wherein the means (160) for electrically connecting comprise at least one electrically conductive element (160) integrated into the elastic and thermally conductive polymer layer (150) to make the elastic and thermally conductive polymer layer (150) electrically conductive.

3. Retaining device arrangement according to claim 2, wherein the at least one electrically conductive element (160) is at least one of metallic nanoparticles or metallic microparticles, carbon-based inclusions, graphite nanoparticles or carbon nanotubes.

4. Retaining device arrangement according to claim 1, wherein the means (260) for electrically connecting comprise at least one metal pin (262) extending through the elastic and thermally conductive polymer layer (150) to the substrate retaining device (110).

5. Retaining device arrangement according to claim 4, wherein each of the at least one metal pin (262) rests on a spring element (264) provided in the substrate retaining device (300).

6. A retaining device arrangement according to claim 5, wherein, in the absence of a substrate, the metal pins (262) protrude at least partially beyond the surface of the elastic and thermally conductive layer (150).

7. A retaining device arrangement according to claim 1, wherein the means (360) for electrically connecting include a conductive layer (362), in particular a metallic layer, provided above the elastic and thermally conductive layer (150) and extending laterally at least partially above the lateral surface of the elastic and thermally conductive polymer layer (150) to be in direct contact with the surface (112) of the substrate retaining device (110).

8. A method for implanting a piezoelectric substrate, in particular a bulk piezoelectric substrate, using a holding device arrangement according to any one of claims 1 to 7, comprising the steps of: a) providing a piezoelectric substrate on the holding device arrangement so as to electrically connect the piezoelectric substrate to a ground potential and, b) implanting atomic species into the piezoelectric substrate.

9. Ion implantation device comprising a holding device arrangement (100, 200, 300) according to any one of claims 1 to 7.

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