DE102005026547B4 - Device for wire-cutting lapping - Google Patents

Abstract

contraption for wire cutting lapping with a pendulum device for a workpiece (8), with which the workpiece related to a pendulum axis by a certain angle along a wire (11) pendulous on a workpiece holder (9) is positioned, a feed unit for the workpiece (8) and Means to run the cutting movement with a wire (11), characterized that the feed unit for the workpiece (8) is arranged after the pendulum axis (5) in front of the workpiece holder (9), so that the feed unit together with the workpiece (8) the Pendulum movement opposite the wire (11) performs.

Description

The The invention relates to a device for wire-cutting lapping the preamble of claim 1.

The Device leaves except for wire cutting lapping also for wire cutting, sheet cutting and sheet cutting deploy.

At the previously used Drahttrennläppen (Wire saws, MWS), the Läppkorn acts along the Eingrifflänge on the entire width of the workpiece. In the direction of the wire speed it comes with this procedure due to the wear of the Läppkornes to a reduction of the effective gap, resulting in an undesirable Wedges of lapped ones Slices leads. Under slices can Semiconductor wafers and other wafers of different materials (e.g., ceramic, aluminum, molybdenum ...) are understood. The shape of the workpiece has no influence on the basic connections.

The Feed rate is low during wire cutting lapping. Limited so far the process the maximum feed rate and not the possibilities the machine. Therefore, any feed rate increase, which the process possible makes, advantage.

Around in the process of wire cutting, which is similar to wire cutting, the highest possible productivity to achieve as possible many grains the minimum chip thickness for the separation of chips necessary to achieve. To change the engagement conditions, the minimum chip thickness can not with all grains be achieved.

The Tiling of the silicon solar disks (disks for the photovoltaic industry) was previously accepted. At present, the production is at medium silicon disk thicknesses of 330 microns well mastered.

at Slices, which for the chip industry are manufactured, plane-parallel surfaces are absolutely necessary. Therefore, the wafers are in an additional manufacturing step lapped planparallel or sanded.

• JP 08-085053 A
• DE 100 64 066 A1
• DE 198 510 70 A1
• WO 02/26431 A1
• US 4727852 A

The prior art includes the following documents which disclose a pendulum device with quasi-point intervention, with the wedging can be avoided. Here, the Quasipunkteingriff is characterized by a shorter Eingrifflänge than the workpiece width.

• JP 08-085053 A
• DE 100 64 066 A1
• DE 198 510 70 A1
• WO 02/26431 A1
• US 4727852 A

• DE 199 59 414 A1
• DE 101 47 634 A1

A Quasipunkteingriff, as occurs in a pendulum workpiece, is also realized in a rotating workpiece. As a pendulum movement with a pendulum angle α = 360 ° and without swing reversal, a rotating workpiece can be considered as a special case and is also listed in some of the above-mentioned publications. In the following documents only the rotation takes place:

• DE 199 59 414 A1
• DE 101 47 634 A1

• DE 100 54 165 A1

Another way to reduce the wedging is to use an oscilation method. The wire movement direction is constantly reversed (oscillate). It creates a mutual wedging towards the middle, as well as a pronounced roughness.

• DE 100 54 165 A1

At the Oszilierverfahren, which is currently used in Drahttrennläppen If a strong roughness occurs, resulting in a lot of effort the subsequent processing results. It will be over 200 for workpieces mm width up to 300 mm width applied. This procedure is with strong scoring on the surfaces connected and eliminated the wedging only indirectly, adding the wedging from scratch to ridge ultimately about the entire disk is distributed and the disk thus macroscopically only has a thickness reduction from the edge towards the middle.

It is the object of the invention to provide a device with which the unwanted wedging we can be significantly reduced, the productivity increased by better material utilization and higher feed rate and constant conditions are achieved during wire cutting through the consistent achievement of minimum chip thickness.

According to the invention Task by a device having the features mentioned in claim 1 solved. Advantageous embodiments of the device are the subject of Dependent claims.

• – ein Prozess unter konstanten Wirkbedingungen führen
• – ein gut zu optimierender Prozess realisieren
• – eine Verringerung der Keiligkeit erzielen
• – eine Verbesserung der Materialausnutzung und eine Steigerung der Produktivität erreichen.

The following advantages can be achieved with the invention:

• - lead a process under constant conditions of action
• - realize a process that is easy to optimize
• - achieve a reduction in the wedging
• - Improve material utilization and increase productivity.

• gleichmäßigere Oberfläche,
• geringere Riefenbildung,
• geringere Welligkeit,
• Verbesserung der Geometriegrößen (TTV und WARP),
• geringe Rauheit und Oberflächenrandzonenschädigung.

At the same time, the following effects are also positive:

• more uniform surface,
• less scoring,
• less ripple,
• Improvement of geometry sizes (TTV and WARP),
• low roughness and surface edge damage.

The Invention will be explained in more detail with reference to exemplary embodiments. In the associated Drawings show:

1 a schematic representation of a pendulum device according to the invention

2 a schematic representation of a pendulum device according to the prior art

3 a representation of the general geometric conditions

4 a representation of the conditions without a constant radius

In the 1 schematically a shuttle according to the invention is shown. Over two wire guide rollers 1 becomes a wire 11 with a certain wire speed 2 guided.

On a swing axle 5 is a feed device with a workpiece holder 9 stored. On the workpiece holder 9 is a workpiece 8th adapted. The workpiece 8th is with the feed device on the wire 11 deliverable. workpiece 8th and feed device lead together around the pendulum axis 5 a pendulum motion.

In the 1 is still the trace of the normal plane 12 to the wire (field) 11 and the track of the parallel plane 13 to the wire (field) 11 shown. The inventive arrangement, the workpiece 8th with a constant pendulum radius R on the wire (field) 11 guided.

Corresponding with the device according to the invention 1 becomes a constant engagement length 19 independent of the feed travel with the aid of the constant pendulum radius 14 realized. This is the pendulum axis 5 in a plane parallel to the wire (field) 11 and in the normal plane to the wire (field) 11 but not on the wire field ( 11 ) ( 2 ). This means that the feed unit is located between pendulum axis and wire (field) 11 ,

If the pendulum axle 5 deviates with a small angle to said normal plane and lies in said parallel plane, a targeted influence on the shape of the discs can be achieved.

If the pendulum axle 5 with a small angle to the parallel plane 13 of the wire (field) 11 deviates and on the said normal level 12 to the wire, also succeeds in a targeted influencing the shape of the discs.

As far as the pendulum axle is concerned 5 Both angle deviations are realized, succeeds in a targeted influencing the shape of the discs.

By the small angular deviation becomes an increased lapping pressure profile perpendicular to the wafer surface applied, resulting in a desired surface profile can generate.

In the prior art devices with a constant pendulum radius 14 not known. Thus, optimization potential is given away, because the process runs in the whole bandwidth of the occurring pendulum, rotation radius.

In the 2 a comparison of the pendulum radii R ₁ and R _{2 is shown} with a device according to the prior art. The pendulum radius decreases during the separation process: R 1 > R 2 (1)

The main disadvantage of such pendulum device or with rotating workpiece 8th lies in the constantly changing engagement length during the process 19 as a result of the constant reduction of the pendulum radius 18 according to Eq. (1) From a finite value to near zero at the center of the workpiece in the direction of feed rate 4 ,

A device according to the invention as shown in the 1 does not have these disadvantages.

From Eq. (2) is with Eq. (1) to recognize that with the pendulum radius R ( 6 . 7 . 18 ) the engagement length l _m ( 19 ) changes.

In order to Pendulum devices according to the prior art have the disadvantage that the conditions at the point of intervention change. With the change the intervention length go other lapping conditions and thus both a different wear behavior of lapping grains than Also associated with other separation conditions.

3 shows the geometric conditions taking into account the wire deflection. It is assumed that the radius of the arc that forms on the workpiece corresponds to the pendulum radius.

It can be the Eingrifflänge l _m 19 be calculated:

As a result the substantial reduction in the wedging of the discs allowed the pendulum wire cutting lapping with the device according to the invention the production of significantly larger workpiece widths over 300 mm out.

As well a substantial increase takes place the material utilization of the very expensive ultrapure silicon by the better production possibility thinner Slices, so-called thin wafers.

Farther increases productivity the lapping process by the substantial increase of lapping pressure at the same previously applied feed force due to a reduced Engagement length. This finding could be confirmed by experiments.

Another disadvantage of the pendulum devices according to the prior art is in 4 shown.

At the Wire cutting can grinding grains because of the changing Engagement conditions can not be avoided because the minimum chip thickness is not reached. Grinding grains do not lift chips wear off unnecessary fast, generate heat and thus come unproductively used.

Constant conditions can be achieved by a device with constant pendulum radius 14 be achieved. There are no engagement lines 22 when the pendulum angle is sufficiently large.

1

Wire guide roll

2

wire speed

3

Pendulum angle α

4

feed rate

5

swing axle

6

Pendulum radius at the beginning of the separation process R ₁

7

Pendulum radius to after some separation progress R ₂

8th

workpiece

9

Workpiece holder

10

pendulum

11

Wire (field) im of process forces uninfluenced state

12

track the normal plane to the wire field

13

track the parallel plane to the wire field

14

constant Pendulum radius R

15

pendulum

17

Wire deflection angle ε

18

swing radius R

19

Intervention length l _m

20

Pendulum angle α ₁

21

Pendulum angle α ₂

22

Just intervention

23

Intervention bow, where a radius is formed

24

leg of the pendulum angle

25

Speed of the processing point at the beginning of the separation process ν _{P, o}

26

Speed of the processing point after some separation progress ν _{P, u}

Claims (7)

Device for wire-cutting lapping with a pendulum device for a workpiece ( 8th ), with which the workpiece is moved by a certain angle along a wire with respect to a pendulum axis ( 11 ) pendulum on a workpiece holder ( 9 ), a feed unit for the workpiece ( 8th ) and means for carrying out the cutting movement with a wire ( 11 ), characterized in that the feed unit for the workpiece ( 8th ) after the pendulum axis ( 5 ) in front of the workpiece holder ( 9 ) is arranged so that the feed unit together with the workpiece ( 8th ) the pendulum movement relative to the wire ( 11 ). Apparatus according to claim 1, characterized in that the pendulum axis ( 5 ) a small angle to the normal plane ( 12 ) and in the parallel plane ( 13 ) lies. Apparatus according to claim 1 or 2, characterized in that the pendulum axis ( 5 ) a small angle to the parallel plane ( 13 ) of the wire ( 11 ) and at the normal level ( 12 ) lies to the wire. Device according to one of claims 1 to 3, characterized in that the workpiece ( 8th ) is rotatably mounted. Device according to one of claims 1 to 4, characterized in that the wire ( 11 ) is rotatably mounted about its own longitudinal axis. Device according to one of claims 1 to 5, characterized in that a scraper for controlling the amount of slurry on the wire ( 11 ) is provided. Device according to one of claims 1 to 6, characterized that the device for wire cutting, Blatttrennläppen or Sheet separation is used.