WAFER/SUPPORT ARRANGEMENT, METHOD FOR PRODUCING THE ARRANGEMENT, AND USE OF THE ARRANGEMENT IN THE PROCESSING OF THE WAFER

Abstract

A wafer/support arrangement, including a wafer, a support system, which includes a support and an elastomer layer, and a connecting layer, wherein the connecting layer is a sol-gel layer. The invention further relates to a coated wafer for a wafer/support arrangement according to the invention, wherein a sol-gel layer is used as a connecting layer for a corresponding wafer/support assembly, and to a method for processing the back side of a wafer.

Claims

1. A wafer/support arrangement, comprising: a wafer, a support system, comprising a support and an elastomer layer, wherein the elastomer layer is aligned with the wafer, and a connecting layer, wherein the connecting layer is a sol-gel layer which can be produced from the monomers (1) Si(OR1).sub.4, and one, two or all of the following monomers (2) Si(OR1).sub.3R2, (3) Si(OR1).sub.2R3R4 and (4) Si(OR1)R5R6R7, wherein each R1 independently of the others represents H or a C.sub.1- C.sub.8 alkyl group, R2, R3, R4, R5, R6 and R7 in each case independently of one another represent a C.sub.1-C.sub.20 alkyl group, a fluorinated C.sub.1-C.sub.20 alkyl group, a C.sub.1-C.sub.20 aminoalkyl group, a C.sub.2-C.sub.20 alkenyl group, an aryl group, a fluorinated aryl group, a single, double or triple C.sub.1-C.sub.4 alkylated aryl, wherein the alkylations are independent of one another with regard to their number of C atoms and/or wherein the group can also be fluorinated, or can represent a C.sub.3-C.sub.20 epoxy group.

2. The wafer/support arrangement according to claim 1, wherein the molar ratio of the monomers (1) to the sum of the quantities of substance of the monomers (2), (3) and (4) is 0.032 (1:31.25) to 1.6 (1.6:1).

3. The wafer/support arrangement according to claim 1, wherein the layer thickness of the connecting layer is 10 to 200 nm.

4. The wafer/support arrangement according to claim 1, wherein each R1 independently of the others represents a C.sub.1-C.sub.3 alkyl group and/or R2, R3, R4, R5, R6 and R7 in each case independently of one another represent a C.sub.1-C.sub.3 alkyl group, a fluorinated C.sub.1-C.sub.3 alkyl group, a C.sub.2-C.sub.3 alkenyl group or phenyl group.

5. The wafer/support arrangement according to claim 1, wherein the elastomer layer is an organosilicon layer.

6. The wafer/support arrangement according to claim 1, wherein the surface with the lowest adhesive force in the arrangement is the interface between the connecting layer and the elastomer layer.

7. The wafer/support arrangement according to claim 1, wherein the wafer on the side directed towards the connecting layer comprises electronic components.

8. The wafer/support arrangement according to claim 1, wherein the support is a glass plate or a second wafer.

9. The wafer/support arrangement according to claim 1, wherein the adhesive force between the connecting layer and the elastomer layer is ≦300 N/m, at a traction speed of in each case [of] 0.1 mm/s.

10. A coated wafer for a wafer/support arrangement according to claim 1, wherein the coating is a connecting layer.

11. The coated wafer according to claim 10, wherein the connecting layer on the side facing away from the wafer has a static water boundary angle of ≧80°, and/or a surface energy of 15-25 mJ/m.sup.2.

12. A connecting layer for the production of a wafer/support arrangement according to claim 1.

13. A method for processing the back side of a wafer, comprising the steps: a) providing a wafer/support arrangement according to claim 1. b) processing the back side of the wafer and c) mechanically separating the wafer/support arrangement along the interface between the elastomer layer and the connecting layer.

14. The method according to claim 13, wherein after step c) the connecting layer is chemically removed from the wafer.

Description

EXAMPLES

Measurement Examples

Measurement Example 1

Ascertaining the Adhesive Force Between the Connecting Layer and the Elastomer Layer

[0078] The wafers connected according to FIG. 1c) are introduced into an apparatus and arrangement according to FIG. 3 and fixed by means of a vacuum to the upper and lower retaining plates. In FIG. 3 the references represent the following: [0079] 1 upper retaining plate [0080] 2 upper vacuum supply [0081] 3 support [0082] 4 elastomer [0083] 5 device wafer with connecting layer (diameter 300 mm) [0084] 6 lower vacuum plate [0085] 7 lower retaining plate [0086] 8 end point [0087] 9 vacuum supply

[0088] The upper retaining plate is designed to be flexible and is made of polycarbonate, brand name Makrolon®, Bayer AG, with a modulus of elasticity of 2.2-2.4 GPa. The plate is 5 mm thick, has a width of 340 mm and is 400 mm long. The retaining plate is affixed so that the introduction of force takes place on the longer side which projects beyond the wafer (diameter 300 mm).

[0089] Before the force measurement, the wafer stack is separated by lifting of this free end of the upper retaining plate in the direction of the arrow as far as the wafer half, so that the separation front which now extends transversely over the wafer has its maximum length. With the further movement of the separation front, the effective length of the free lever arm, and thus also the force measured at the measurement point along the direction of the arrow, is extended. The maximum measured tensile force is used as a measured value which is produced empirically at an effective length of the lever arm of for instance 245 mm. In this case the point of application of force on the lever arm is 95 mm away from the edge of the wafer. In wafers which have a diameter different from 300 mm, in the determination of the adhesive force a recalculation is based on a 300 mm-diameter wafer, wherein the person skilled in the art includes both the changed lever length and also the changed length of the separation front in the calculation.

Measurement Example 2

Determination of the Water Boundary Angle

[0090] The static water boundary angle is determined according to DIN 55660-2:2011-12.

Measurement Example 3

Determination of the Surface Energy

[0091] The surface energy (free surface energy) is determined according to DIN 55660-2:2011-12.

Measurement Example 4

Determination of the Water Sliding Angle

[0092] The wafer is fixed on a tilt plate. Subsequently a drop of water (deionized and particle-filtered (0.22 μm), Waters-Millipore, Milli-Q), either 50 μL, 25 μL or 10 μL, is applied to the wafer. The angle at which the drop of water begins to move slowly is determined. Overall three measurement cycles are carried out for each drop size. Preferred values extend from 10-13° for 50-μL drops of water, and/or 18-25° for 25-μL drops and/or 28-55° for 10-μL drops over the cured connecting layers,

[0093] In case of doubt, the water sliding angle is determined as described in this measurement example in particular for 25 μL.

Exemplary Embodiments

Example 1

[0094] Isopropanol (IPA, 99.8% Carl Roth) (97.75% by volume), tetraethoxysilane (TEOS, ≧99.0%, Sigma-Aldrich) (0.5% by volume) and methyltrimethoxysilane (MTMS, ≧98.0%, Sigma-Aldrich) (1.5% by volume) are mixed. Next the activator (Brönsted or Lewis acid, base or fluoride ion), in this case 0.25% by volume of tetramethylammonium hydroxide (TMAH 2.38% by weight in H.sub.2O, Micro Chemicals), is added. [0095] The activity is checked before use by a dip-coat. For this purpose, an elongated (approximately 1×5 cm) part of a new untreated silicon wafer is briefly immersed in the solution. If a layer forms during drying of the precursor, the solution is suitable for spin-coating. The time until activation is a few minutes up to several days, depending upon the concentration and the activator content. [0096] The wafer to be treated is completely covered with precursor (approximately 10 mL for a 200-mm wafer, approximately 20 mL for a 300-mm wafer) and after approximately 30 seconds standing time is spun for 20 seconds at 1000 rpm. [0097] Subsequently the still-moist layer is tempered at 165° C. for 10 minutes, so that the layer thickness decreases from initially 60-80 nm to 40-60 nm, and the layer is solid. The water sliding angle (50-μL drops) is now 10-13°, the water contact angle (10-μL drops, static) 95-105°. [0098] A second silicon wafer is coated with addition-crosslinking silicone adhesive, and both wafers are connected in the bonding chamber at reduced pressure (for instance 0.3 mbar) by “force-free bonding” (as described in WO 2010/061004 A1). [0099] After 10 minutes curing of the silicone adhesive, the wafer stack can be subjected to further processes. [0100] For separating the wafer stack, initiation takes place at one location, i.e. one small part of the wafer is detached from the other. Subsequently the lower wafer fixed on a vacuum plate is separated from a second vacuum panel. In this case the sol-gel layer remains on the device wafer, the separation takes place between the sol-gel release layer and the silicone adhesive. [0101] For removal of this layer, the wafer is placed with agitated dipping for 10-20 minutes in a solution of 2.5% by weight tetrabutylammonium fluoride (TBAF, 97%, Sigma-Aldrich) in methylisobutyl ketone (MIBK) and is then washed with isopropanol. [0102] Alternatively, a wafer provided with a sol-gel layer is divided into 4×4 cm pieces, and the pieces are placed in the etching solution (static dipping). The values for static dipping are lower than the values for agitated dipping and cannot be directly compared. [0103] In this case the layer is resistant to organic solvents such as acetone, isopropanol, MIBK, gasoline, but also to water, aromatic hydrocarbons and chlorinated hydrocarbons. Only the combination of organic solvents and etching agent (TBAF) dissolved therein leads to removal.

Example 2

Alternatively Mixture for the Connecting Layer

[0104] 94.15% by volume IPA [0105] 2.5% by volume TEOS [0106] 2.5% by volume MTMS [0107] 0.6% by volume Water (H.sub.2O) [0108] 0.25% by volume hydrochloric acid (HCl.sub.aq, 0.95% by weight diluted from 1M standard solution, Carl Roth)

Example 3

Alternative Mixture for the Connecting Layer

[0109] 97.25% by volume isopropanol [0110] 0.5% by volume TEOS [0111] 1% by volume MTMS [0112] 1% by volume hexadecyltrimethoxysilane (HDTMS, ABCR Research Chemicals) [1641512-6] or [0113] 1H,1H,2H,2H-perfluorooctyltrie hoxys lane (FAS, ABCR Research Chemicals) ( ) [51851-37-7] [0114] 0.25% by volume TMAH

[0115] The chemicals in Examples 2 and 3 correspond to those of Example 1, unless specified otherwise.

Example 4

Water Boundary Angle

[0116] According to measurement examples 2 and 3, the following values (Table 1) were measured for the layers of Examples 1 to 3 after curing

TABLE-US-00001 Water boundary Water sliding angle [°] angle [°] 50 μL 25 μL 10 μL Example 1 84 12 21 40 Example 2 80 13 25 52 Example 3 91 11 22 48

Example 5

Agitated Dipping

[0117] The 300-mm (diameter) large wafer provided with a sol-gel layer is fixed on an agitator plate, and incubated in 300 mL cleaning solution. The cleaning solutions used can be seen from FIG. 4. Before and after the cleaning procedure the layer thickness of the sol-gel layer is determined with an interferometer, and from the action time and the reduction in layer thickness the etching rate is determined according to

etching rate=reduction in layer thickness/time.

[0118] It was found that general solutions containing TBAF are preferable as cleaning agents.

Example 6

Static Dipping

[0119] A 4×4 centimeter large wafer piece provided with a sol-gel layer is placed in 50 mL etching solution. In this case a movement of the solution is omitted. The etching rate is determined according to the equation given in Example 5. Due to the lack of movement of the solution, the etching rates are lower than in the case of agitated dipping (Example 5).