DE10301245A1 - Method of processing a workpiece and attaching to a carrier especially for silicon semiconductor wafers permits a simple separation and handling - Google Patents

Abstract

Among other things, a method is explained in which a workpiece (14) is fastened to a workpiece carrier (12) with the aid of connecting means (18, 20). The resulting combination is processed. The machined workpiece (14) is then separated from the workpiece carrier (12) by dividing the workpiece carrier (12). A particularly simple processing method is created.

Description

• – Befestigen eines Werkstücks an einem Werkstückträger,
• – Bearbeiten des am Werkstückträger befestigten Werkstücks, und
• – Trennen des bearbeiteten Werkstücks vom Werkstückträger.

The invention relates to methods in which the following steps are carried out:

• - attaching a workpiece to a workpiece carrier,
• - Machining the workpiece attached to the workpiece carrier, and
• - Separation of the machined workpiece from the workpiece carrier.

The workpiece is, for example, a semiconductor substrate made of a semiconductor material, e.g. made of silicon. Such a semiconductor substrate is also called a wafer. The workpiece carrier is, for example Foil or other suitable material. When editing the workpiece for example thinned.

The fastener is preferably between the workpiece and arranged the workpiece carrier, to enable unhindered machining of the workpiece and also to connect guarantee for workpieces at risk of breakage.

So is from the Japanese patent application JP 04-188818 A a semiconductor wafer known for easy handling on a reinforcing material is glued, e.g. on a polyimide film.

It is an object of the invention specify a simple method for machining a workpiece on a workpiece carrier, which in particular enables simple separation and / or that in particular machining at temperatures up to 200 ° C or up to a temperature above 200 ° C allowed.

This task is carried out according to a first aspect of the invention by that specified in claim 1 Process steps solved.

The invention is based on the consideration from that for example back processes on thin wafers lead to problems in handling the wafers. Thin wafers are special Wafers with a thickness of less than 300 μm. The handling problems are as the diameter of the wafers increases, i.e. especially at Wafers with a diameter between 100 mm and 300 mm or with with a diameter greater than 300 mm. Despite an adaptation of processing systems to the processing from thin Many remain in wafers and despite the effort involved Handling disadvantages, especially an additional operating effort, a increased Risk of breakage and restrictions in processing.

• – Beibehaltung eines einfachen Bearbeitungsprozesses,
• – Gewährleisten einer hohen Bearbeitungstemperatur, und
• – ein einfaches Lösen des Trägers ohne Bruchgefahr für den Wafer.

The invention is also based on the consideration that a variety of carrier systems are conceivable so that the wafer, supported on a carrier, can be stable and handled. However, there are a number of problems to be solved at the same time:

• - maintaining a simple machining process,
• - ensuring a high processing temperature, and
• - a simple release of the carrier without risk of breakage for the wafer.

Therefore, in the method according to the invention additionally the workpiece from the workpiece carrier to the above-mentioned method steps Removal of parts of the workpiece and / or of the workpiece carrier in separated at least one separation area. In one configuration becomes when removing parts of the workpiece or the workpiece carrier workpiece or the workpiece carrier in at least divided into two parts. In the method according to the invention, the workpiece and workpiece carrier are not the whole area connected to each other, but only over partial areas, between which none Lanyards are arranged. This enables separating cuts to be made around the connecting surfaces perform or the connecting surfaces Completely ablate.

Thus, in a configuration for a workpiece, the is a semiconductor wafer, also a semiconductor wafer as workpiece carrier used, e.g. a so-called dummy wafer or one no longer needed Test wafers. The thickness of the workpiece carrier wafer is arbitrary. The carrier wafer let yourself on the workpiece wafer before or only after thinning of the workpiece wafer Fasten. The width of a gap between the workpiece wafer and the carrier wafer is for the implementation of the method according to the invention not critical, so no tolerances for this either Gap must be observed. In one embodiment, however, without Gap between workpiece and workpiece carriers worked. Consist both wafers made of silicon, for example, the thermal expansion coefficients are also the same. Moreover can carrier wafer can be used, which are a by-product of semiconductor manufacturing and therefore not make the procedure more expensive.

In the design, the workpiece wafer in some places with the carrier wafer connected by a high temperature resistant substance, for example in four places. A connection means is, for example, a connection means suitable, which consists of palladium or contains palladium. The connection points can are, for example, on the edge of the wafers, i.e. outside the active chip area. In another embodiment, however, there are connection points also in the center of the wafers. The connections are resistant to high temperatures and can solved if necessary become. In one configuration, however, the connections are not released required because around or at the junctions is separated. If you separate at the connection points, then the connection is destroyed.

The workpiece wafer can be combined with the workpiece wafer and carrier wafer Commercially available systems continue to work, e.g. with an ion implanter, with a CVD system (Chemical Vapor Deposition), with a sputtering system, with an exposure system, in a lithography process or in an oven process or in a thermal radiation process, e.g. in an RTP process (Rapid Thermal annealing). Due to the increased thickness of the composite of workpiece wafer and carrier wafer, there are no longer any handling problems.

With a further education is along a separation area separated, which encloses a fastening part on which a connecting means for connecting the workpiece and workpiece carrier is attached, in particular a connecting means in a central part of the workpiece or of the workpiece carrier. The the actual connection remains undamaged.

In an alternative embodiment is separated along a separation area, which together with the Edge of the workpiece or the workpiece carrier one Fastening part encloses, to which a connecting means is attached. This configuration is particularly used for lanyards on the edge of the workpiece or the workpiece carrier arranged are. In this case too, the actual connection remains undamaged is separated around them.

In a further alternative embodiment contains the separation area is an interface between the workpiece or the workpiece carrier on the one side and a lanyard on the other side. The interface and thus also becomes part of the connection or the entire connection destroyed when disconnected, which disconnected becomes.

The next training course will have the workpiece and workpiece carrier same outline. This measure allows processing plants for certain Workpiece thickness even when the workpieces are thinner. Modifications are not required because the thickness and the outline of the composite of workpiece and workpiece carrier Thickness and the outline of an undiluted workpiece correspond.

In one configuration, the workpiece or workpiece carrier are angular Plates or round disks, in particular semiconductor wafers with a so-called flat or a notch to identify a crystal direction.

In a next design, there are workpiece carriers and workpiece from the same material or the same material composition, so temperature processes can be done without additional stresses the connection or due to the bond with the workpiece carrier.

Is there a next design workpiece made of a semiconductor material, so when processing a process performed for processing semiconductor material, in particular a lithography process, a metallization process, a layer application process, a layer structuring method, an implantation method, an oven process or a thermal radiation process.

The processing procedures will be on another Design on the back of the workpiece carried out, i.e. on a side that contains no active components, such as e.g. Transistors.

The next training course will be sawing or Loops separated. These methods are particularly useful for workpieces or Workpiece carriers Glass, ceramic or made of semiconductor materials. At a A straight cut is created, for example when using a straight saw blade or a circular saw blade arises. However, circular saw blades can also be used to saw out the Use connection points.

Another training course workpiece and workpiece carriers at only two edge areas connected together. When disconnecting only two cuts, which are preferably parallel to each other.

With alternative training are the workpiece and the workpiece carrier at only four edge areas connected to each other. When disconnecting only four cuts, preferably along the outline of a rectangle or a Square. In an alternative embodiment with a Connection at only four edge areas, eight cuts are made preferably along the outlines of two rectangles or two squares with different sizes. Due to a small number of connection points and separating cuts the procedure is simplified considerably.

The next training course will take place after To run at least one cutting process a separated part of the workpiece or removed from the workpiece carrier, before the next one Cutting process on the same workpiece or the same workpiece carrier is executed. For example, lets take up the separated part. Suitable devices for Are removing blowers or suction devices.

In a next training, the workpiece is during the Removed attached to a holding means. Is suitable for one Design a self-adhesive film, e.g. a so-called saw foil.

In a next embodiment, according to the Cutting the workpiece and workpiece carrier Another method for separating a variety of components of the workpiece carried out. This means that when cutting the workpiece and workpiece carrier, none Separating cuts for separating or not all separating cuts for separating have been carried out are.

In a next embodiment, the Only separate parts of the workpiece carrier, but not of the workpiece ablated. This leaves can be reached, for example, if the cutting tool is only up to a gap between the workpiece and penetrates the workpiece carrier. In another embodiment, the cutting tool only penetrates part of the workpiece carrier. The whole Cutting the workpiece and workpiece carrier achieved by the vibration occurring during separation. In this In one embodiment, the case also has no gap between workpiece and workpiece carriers worked.

In a next development, the workpiece and workpiece carrier are together glued, welded or soldered. Gluing leaves for example with the help of wax or an adhesive on both sides Carry out foil.

In a next development, the workpiece and workpiece carrier will be together glued, the adhesive connection temperature resistant up to 200 ° C or up to 400 ° C or up to 800 ° C or even up to 1200 ° C is. Despite this high temperature resistance, low temperatures Temperatures are separated due to the separation process explained above.

In one embodiment, a Conductive adhesive used, for example, built on a silver base is. Such conductive adhesives are for example for heaters on car windows known. The temperature resistance of the adhesive is increased if palladium is added or if the adhesive is fully on a palladium base. With increasing palladium content the temperature resistance increases.

The invention relates in a further Aspect as well a process with the above-mentioned process steps, at between the workpiece and the workpiece carrier at least a fastener is arranged. The fastener is tel temperature stable for Temperatures up to 200 ° C (Degrees Celsius) or up to 400 ° C or up to 800 ° C or even up to 1200 ° C. When machining the workpiece a high temperature process is carried out in which the temperature in order for the aforementioned temperatures, for example, greater than 150 ° C, greater than 350 ° C, greater than 700 ° C or larger than Is 1000 ° C. Cutting workpiece and workpiece carrier however carried out at a temperature below the machining temperature lies. For example, lets perform a separation process according to the first aspect. however can selective etching can also be used to separate, which only the connecting means, but not the workpiece carrier and especially not the workpiece attack.

In a further development of the procedure according to the second Aspect is used as a fastener a conductive adhesive with the above Properties used, especially a conductive adhesive based on palladium.

The workpiece or the workpiece carrier are in the method according to the second Aspect as in the method according to the first Aspect trained.

In the following, exemplary embodiments of the Invention explained with reference to the accompanying drawings. In this demonstrate:

1 a composite of carrier wafer and workpiece wafer,

2 Separating cuts for a composite with four circular connection points,

3 Separation cuts for a composite with four circular sector-shaped connection areas,

4 Separation cuts for a composite with two circular segment-shaped connection areas, and

5 Separation cuts for a composite with a connection area.

1 shows a composite 10 a carrier wafer 12 and a workpiece wafer to be processed 14 , The workpiece wafer 14 has a front 16 , on which a large number of integrated circuits have been produced, for example CMOS circuits (Complementary Metal Oxide Semiconductor). The front 16 is the carrier wafer 12 facing and with the help of conductive adhesive 18 and 20 , eg based on palladium on the carrier wafer 12 attached. After gluing carrier wafers 12 and workpiece wafers 14 became the workpiece wafer 14 at its back 22 thinned, for example with the help of a grinding system by more than 100 μm. After thinning, the back was 22 for example with a rear contact. A temperature process is carried out with a processing temperature greater than 350 ° C or greater than 450 ° C. Then the back 22 on a saw foil 24 glued to a saw frame 26 is attached.

After attaching the composite 10 on the saw frame 26 first becomes the carrier wafer 12 from the thinned workpiece wafer 14 removed by making two saw cuts, see dashed lines 28 and 30 , The saw cuts are carried out simultaneously or one after the other. When sawing only the carrier wafer 12 severed, but not the workpiece wafer 14 , This can be due to a gap 32 between carrier wafers 12 and ensure workpiece wafers easily.

After removing the carrier wafer 12 from the workpiece wafer 14 the integrated circuits on the workpiece wafer 14 isolated, tested and provided with a housing using the known sawing methods.

2 shows a plan view of a composite 50 from a carrier wafer 52 and one under the carrier wafer 52 arranged workpiece wafer. The carrier wafer 52 is on the workpiece wafer with the help of four punctiform adhesive connections 54 to 60 attached. The adhesive connections 54 to 60 lie on the edge of the carrier wafer 52 at the corners of a square.

There are eight straight saw cuts in succession 62 to 76 carried out. For example, the saw blade has a width of only 25 μm (micrometers), so that a saw cut of approximately 35 μm is produced. As soon as parts of the carrier wafer 52 solve, they are picked up by a recording device, for example by an extraction system. The saw cuts 62 to 68 are parallel to each other and in the order mentioned to the left of the adhesive connections 54 and 60 , immediately to the right of the adhesive connections 54 and 60 , immediately to the left of the adhesive connections 56 and 58 and to the right of the adhesive connections 56 and 58 , The saw cuts 70 to 76 are also parallel to each other and in the order mentioned above the adhesive connections 54 and 56 , immediately below the adhesive connections 54 and 56 , immediately above the adhesive connections 60 and 58 as well as below the adhesive connections 60 and 58 ,

In an alternative development, the adhesive connections 54 to 60 burned away with the help of a laser beam, the carrier wafer 52 and also pierce the workpiece wafer. In this case, the carrier wafer 52 reuse in other manufacturing processes as carrier wafers.

3 shows a plan view of a composite 80 from a carrier wafer 82 and a workpiece wafer underneath. carrier wafer 82 and workpiece wafers are made using four adhesive bonds 84 to 90 glued together, for example with the help of conductive glue or with the help of a non-conductive glue. The adhesive connections 84 to 90 have quarter-circular cross-sections along a cross-sectional plane that is parallel to the plane in which the carrier wafer is also located 82 extends. The adhesive connections 84 to 90 lie on the edge of the carrier wafer 82 at the corner points of a square.

For separating carrier wafers 82 and workpiece wafers become four separating cuts 92 to 98 executed. First, the separating cuts are made simultaneously 92 and 94 executed that are parallel to each other. The parting cut 92 borders on the adhesive connections 84 and 90 , The parting cut 94 borders on the adhesive connections 86 and 88 , After making the separating cuts 92 and 94 becomes a strip A of the carrier wafer 82 removed, for example with the aid of a blower. Then the separating cuts are made simultaneously 96 and 98 performed, which are also parallel to each other, but perpendicular to the separating cuts 92 and 94 lie. The parting cut 96 borders on the adhesive connections 84 and 86 , The parting cut 98 borders on the adhesive connections 88 and 90 , When making the separating cuts 96 and 98 are two segments B of the network 80 solved, which are removed from the composite, for example with the aid of a blower.

In an alternative embodiment, the strip A is cut before making the separating cuts 96 and 98 not removed. This will make strip A when making the separating cuts 96 and 98 separated into three parts. The parts of the carrier wafer that were created during the cutting process 82 after making all the separating cuts 92 to 98 peeled off with the help of an adhesive film.

In another embodiment, only the four are shown in FIG 3 explained separating cuts 92 to 98 also with the in 2 shown composite 50 carried out.

4 shows a plan view of a composite 100 from a carrier wafer 102 and a workpiece wafer underneath. The carrier wafer 102 is with the help of two adhesive connections 104 and 106 attached to the workpiece wafer. The adhesive connections 104 and 106 are each in the form of a segment of a circle and lie on edge regions of the carrier wafer 102 or the workpiece wafer, which lie on opposite sides of a diameter. For separating the carrier wafer 102 from the association 100 two simultaneous separating cuts are made simultaneously or successively 108 and 110 executed. The parting cut 108 runs along the straight side of the circle segment of the adhesive connection 104 , The parting cut 110 runs along the straight sides of the circular segment of the adhesive connection 106 ,

5 shows a composite 120 from a rectangular carrier substrate 122 and a rectangular workpiece substrate to be processed arranged underneath. carrier substrate 122 and workpiece substrate are made of ceramic, for example. At the center of the network 120 there is an adhesive connection 124 with circular cross section. For separating the carrier substrate 122 from the association 120 the carrier substrate is, for example, with the help of a perforated grinding wheel 122 along the circumference of the adhesive connection 124 separated, see separation circuit 126 , Alternatively, the composite can be 120 pick up a hole through the carrier substrate using a laser or a drill 122 and possibly also through the workpiece substrate within the dividing line 126 is burned or drilled.

The procedures explained can be especially on thin ones carrier substrates do well. For example, the carrier substrates thinner than 1 mm. Moreover all processes can also be carried out with separating cuts that both the workpiece as well as penetrate the workpiece carrier.

In another exemplary embodiment, the workpiece wafer is located above the carrier wafer. This means that the carrier wafer is glued to the saw foil. This variant is used in particular when only a part has to be solved, as is the case with the 4 and 5 explained variants is the case.

• – sehr preiswert durchführbar,
• – für Träger mit einfach lösbaren Verbindungen geeignet,
• – für hochtemperaturfeste Verbindungen geeignet, und
• - sehr einfach auszuführen.

The procedures explained are:

• - very inexpensive to carry out,
• - suitable for carriers with easily detachable connections,
• - Suitable for high temperature resistant connections, and
• - very easy to do.

10

composite

12

carrier wafer

14

Workpiece wafer

16

front

18 20

conductive adhesive

22

back

24

sawing film

26

saw frame

28 30

sawing line

32

gap

50

composite

52

carrier wafer

54 to 60

adhesive bond

62 to 76

Saw cut

80

composite

82

carrier wafer

84 to 90

adhesive bond

92 to 98

separating cut

A

strip

B

segment

100

composite

102

carrier wafer

104 106

adhesive bond

108 110

separating cut

120

composite

122

carrier substrate

124

adhesive bond

126

separating cut

Claims (12)

Process for machining a workpiece ( 14 ) on a workpiece carrier ( 12 ) in which the following steps are carried out without limitation in the order specified: fastening a workpiece ( 14 ) on a workpiece carrier ( 12 ), Machining the on the workpiece carrier ( 12 ) attached workpiece ( 14 ), and separating the machined workpiece ( 14 ) from the workpiece carrier ( 12 ), the workpiece ( 14 ) from the workpiece carrier ( 12 ) by removing parts of the workpiece ( 14 ) and / or the workpiece carrier ( 12 ) in at least one separation area ( 28 . 30 ) is separated. A method according to claim 1, characterized in that along a separation area ( 126 ) is separated, which encloses a fastening part on which a connecting means ( 124 ) for connecting workpiece and workpiece carrier ( 122 ) and / or that along a separation area ( 28 . 30 ) which is shared with the edge of the workpiece ( 14 ) or the workpiece carrier ( 12 ) encloses a fastening part on which a connecting means ( 18 . 20 ) for joining workpiece ( 14 ) and workpiece carrier ( 12 ) and / or that the separation area ( 126 ) an interface of a fastening area of the workpiece or workpiece carrier ( 122 ) and a lanyard ( 126 ) for connecting workpiece and workpiece carrier ( 122 ) contains. A method according to claim 1 or 2, characterized in that the workpiece ( 14 ) and the workpiece carrier ( 12 ) have the same outline and / or that the workpiece ( 19 ) and / or the workpiece carrier ( 12 ) are square plates or round disks, preferably flattened disks on one circumferential side, and / or that the workpiece ( 14 ) and the workpiece carrier ( 12 ) consist of the same material or of the same material composition, and / or that the workpiece ( 14 ) contains a semiconductor material or consists of a semiconductor material, and / or that the workpiece carrier ( 12 ) contains a semiconductor material or consists of a semiconductor material, and / or that a lithography method and / or a metallization method and / or a layer application method and / or a layer structuring method and / or an implantation method and / or an oven process and / or a temperature irradiation process is carried out during processing , especially on the back ( 22 ) of the workpiece ( 14 ). Method according to one of the preceding claims, characterized in that it is separated by sawing or grinding, and / or that a straight separating cut ( 28 . 30 ) is produced. A method according to claim 4, characterized in that the workpiece and the workpiece carrier ( 102 ) at only two separation areas ( 104 . 106 ) and that the workpiece and workpiece carrier ( 102 ) with just two cuts ( 108 . 110 ) are separated, which are preferably parallel to each other. A method according to claim 4, characterized in that the workpiece and the workpiece carrier ( 52 . 82 ) are connected to each other at only four edge areas, and / or that with only four separating cuts ( 92 to 98 ), which are preferably along the outline of a rectangle or a square, and / or that with only eight separating cuts ( 62 to 76 ) is separated, which preferably lie along the outlines of two rectangles or two squares. Method according to one of the preceding claims, characterized in that a part (A, B) of the workpiece or the workpiece carrier ( 82 ) is removed before the next cutting process on the same workpiece or the same workpiece carrier ( 82 ) is performed. Method according to one of the preceding claims, characterized in that the workpiece ( 14 ) during removal on a holding device ( 24 ) is attached, preferably to a self-adhesive film, in particular to a sawing film, and / or after the workpiece has been separated ( 14 ) and workpiece carrier ( 12 ) further separating processes for separating a large number of components or circuits of the workpiece ( 14 ) and / or that only parts of the workpiece carrier ( 12 ), but not the workpiece ( 14 ) are removed, preferably a complete separation of the workpiece carrier ( 12 ) is achieved by the vibration occurring during separation. Method according to one of the preceding claims, characterized in that the workpiece ( 14 ) and the workpiece carrier ( 12 ) are glued or welded or soldered together. Method according to one of the preceding claims, characterized in that the workpiece ( 14 ) and the workpiece carrier ( 12 ) are glued together, the adhesive connection being temperature resistant up to 200 ° C or up to 400 ° C or up to 800 ° C or up to 1200 ° C, preferably a conductive adhesive ( 18 . 20 ) is used, in particular a conductive adhesive based on silver and / or palladium. Process for machining a workpiece ( 14 ) on a workpiece carrier ( 12 ) in which the following steps are carried out without limitation in the order specified: fastening a workpiece ( 14 ) on a workpiece carrier ( 12 ), Machining the on the workpiece carrier ( 12 ) attached workpiece ( 14 ), and separating the machined workpiece ( 14 ) from the workpiece carrier ( 12 ), at least one fastener ( 18 . 20 ) between the workpiece ( 14 ) and the workpiece carrier ( 12 ) is arranged, the fastening means ( 18 . 20 ) is temperature stable for temperatures up to 200 ° C or up to 400 ° C or up to 800 ° C or up to 1200 ° C, the workpiece at a processing temperature of at least 150 ° C or at least 350 ° C or at least 700 ° C or at least 1000 ° C, and the workpiece ( 14 ) and the workpiece carrier ( 12 ) are separated from each other at a temperature that is below the processing temperature. A method according to claim 11, characterized in that as a fastening means ( 18 . 20 ) a conductive adhesive is used, in particular a conductive adhesive based on silver and / or on palladium.