JP2016054182A - Processing method for wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a processing method for a wafer by dividing a wafer without exfoliating a Low-k film even when the Low-k film is directly cut along a predetermined dividing line that is formed on the wafer by a cutting blade, without dividing the Low-k film by irradiating it with a laser beam along the predetermined dividing line.SOLUTION: The processing method includes: a wafer holding step of holding a rear side of a wafer 10 in workpiece holding means 3 of a cutting device; and a Low-k film cutting step of cutting at least a Low-k film along the predetermined cutting line of the wafer held by the workpiece holding means 3 by relatively feeding the workpiece holding means 3 and a cutting blade 43 that includes a cutting edge in an outer circumference and is rotated at high speed, for processing while positioning the cutting blade 43 along the predetermined dividing line. In the Low-k film cutting step, cutting water containing an organic acid and an oxidant is supplied to an area to be cut by the cutting edge of the cutting blade 43.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a wafer processing method in which devices are formed in a plurality of regions partitioned by a plurality of division lines formed in a lattice pattern on a low-k film stacked on the surface of a semiconductor substrate.

  As is well known to those skilled in the art, in a semiconductor device manufacturing process, a semiconductor in which a plurality of devices such as ICs and LSIs are formed in a matrix by a functional layer in which an insulating film and a functional film are laminated on the surface of a semiconductor substrate such as silicon. A wafer is formed. The semiconductor wafer formed in this way is partitioned by the planned division lines in which the above devices are formed in a lattice shape, and individual semiconductor devices are manufactured by dividing along the predetermined division lines.

  Recently, in order to improve the processing capability of semiconductor chips such as IC and LSI, inorganic films such as SiOF and BSG (SiOB) and polymers such as polyimide and parylene are used on the surface of a semiconductor substrate such as silicon. A semiconductor wafer having a form in which a device is formed by a laminated body in which a low dielectric constant insulating film made of an organic film, which is a film, and a metal foil such as copper or aluminum are intertwined has been put into practical use. A laminate in which the low dielectric constant insulator film and the metal foil such as copper and aluminum are entangled with each other is called a Low-k film, and the Low-k film is also laminated on the planned dividing line. Yes.

  Such a division of the semiconductor wafer along the division line is usually performed by a cutting device called a dicer. This cutting apparatus includes a chuck table for holding a semiconductor wafer as a workpiece, a cutting means for cutting the semiconductor wafer held on the chuck table, and a movement for relatively moving the chuck table and the cutting means. Means. The cutting means includes a rotating spindle that is rotated at a high speed and a cutting blade attached to the spindle. The cutting blade is composed of a disk-shaped base and an annular cutting edge mounted on the outer periphery of the side surface of the base. The cutting edge is formed by fixing diamond abrasive grains having a grain size of about 3 μm, for example, by electroforming. ing.

  However, the Low-k film described above is difficult to cut with a cutting blade. In other words, the low-k film is very brittle like mica, so when the cutting blade is cut along the planned dividing line, the low-k film is peeled off, and this peeling reaches the circuit, resulting in fatal damage to the device. There is a problem of giving.

  In order to solve the above problem, the low-k film is removed and divided by irradiating a laser beam along a planned division line formed on the semiconductor wafer and forming a laser processing groove along the planned division line. Patent Document 1 below discloses a wafer dividing method in which a cutting blade is positioned in a laser processing groove and the cutting blade and the semiconductor wafer are moved relative to each other to cut the semiconductor wafer along a planned dividing line.

However, as described above, when the laser beam is irradiated along the planned division line formed on the semiconductor wafer and the low-k film is removed along the planned division line, the laser processing groove is formed on the substrate. Therefore, there is a problem that strain remains and the bending strength of the device is lowered.
In addition, when laser light is irradiated along the planned division line of the semiconductor wafer, thermal energy concentrates on the irradiated area and debris is generated, and this debris adheres to the surface of the device and degrades the device quality. The surface of the semiconductor wafer is covered with a protective film such as polyvinyl alcohol, and the semiconductor wafer is irradiated with a laser beam through the protective film (see, for example, Patent Document 2).

JP-A-2005-64231 JP 2006-286863 A

  Thus, in the technique disclosed in Patent Document 2, there is a problem that a process for coating the surface of the semiconductor wafer with a protective film has to be performed, resulting in poor productivity and increased equipment costs.

  The present invention has been made in view of the above-mentioned facts, and its main technical problem is to divide the line to be divided without dividing the Low-k film by irradiating the laser beam along the line to be divided formed on the wafer. A method of processing a wafer that can be cut without peeling off the Low-k film even if the Low-k film is cut directly with a cutting blade along the line.

In order to solve the above-mentioned main technical problem, according to the present invention, devices are provided in a plurality of regions partitioned by a plurality of division lines formed in a lattice pattern on a low-k film stacked on the surface of a semiconductor substrate. A method of processing a formed wafer,
A wafer holding step for holding the back side of the wafer in the workpiece holding means of the cutting device;
A cutting blade having a cutting edge on the outer periphery is positioned on a scheduled division line of the wafer held by the workpiece holding means, and a high-speed rotating cutting blade is positioned, and the workpiece holding means and the cutting blade are relatively processed and fed. A low-k film cutting step that divides at least the low-k film along the planned dividing line,
In the Low-k film cutting step, cutting water containing an organic acid and an oxidizing agent is supplied to a cutting region by the cutting blade of the cutting blade.
A method for processing a wafer is provided.

It is desirable that an anticorrosive agent is mixed in the cutting water.
In the low-k film cutting step, the semiconductor substrate is cut along the planned division line together with the low-k film.
In addition, after performing the Low-k film cutting step, a cutting step is performed in which the Low-k film is divided and the semiconductor substrate exposed along the planned division line is cut along the planned division line.

  In the method of processing a wafer according to the present invention, a cutting blade having a cutting edge on the outer periphery and positioned at a high speed is positioned on a planned division line of the wafer held by the workpiece holding means, and the workpiece holding means and the cutting blade are arranged. The low-k film cutting process in which at least the low-k film is divided along the line to be divided by processing and feeding relatively, the cutting water containing the organic acid and the oxidizing agent is cut by the cutting edge of the cutting blade. Since the metal foil constituting the Low-k film is modified by the oxidizing agent contained in the cutting water to suppress ductility, the metal foil becomes brittle with the organic acid and the workability is promoted. Therefore, the Low-k film is cut without peeling.

The perspective view of the cutting device for enforcing the processing method of the wafer by the present invention. The figure which shows the principal part of the cutting means with which the cutting apparatus shown in FIG. 1 is equipped, and the cutting water supply mechanism. 1 is a perspective view of a semiconductor wafer as a wafer processed by the wafer processing method according to the present invention and a cross-sectional view showing an enlarged main part. The perspective view which shows the state which affixed the dicing tape on the back surface of the semiconductor substrate which comprises the semiconductor wafer shown in FIG. 3, and supported the outer peripheral part of the dicing tape with the cyclic | annular flame | frame. Explanatory drawing of the Low-k film | membrane cutting process in the processing method of the wafer by this invention. Explanatory drawing which shows the state by which the cutting water containing an organic acid and an oxidizing agent is supplied to the cutting area | region by the cutting blade of a cutting blade in the Low-k film | membrane cutting process shown in FIG. Explanatory drawing which shows other embodiment of the Low-k film | membrane cutting process in the processing method of the wafer by this invention. Explanatory drawing which shows 1st Embodiment of the cutting process in the processing method of the wafer by this invention. The principal part perspective view of the laser processing apparatus for implementing 2nd Embodiment for implementing the cutting process in the processing method of the wafer by this invention. Explanatory drawing which shows 2nd Embodiment for implementing the cutting process in the processing method of the wafer by this invention.

  Preferred embodiments of a wafer processing method according to the present invention will be described below in more detail with reference to the accompanying drawings.

  FIG. 1 is a perspective view of a cutting apparatus for carrying out the wafer processing method according to the present invention. A cutting device 1 shown in FIG. 1 includes a device housing 2 having a substantially rectangular parallelepiped shape. In the apparatus housing 2, a chuck table 3 as a work holding means for holding a work is disposed so as to be movable in a direction (X-axis direction) indicated by an arrow X which is a cutting feed direction. The chuck table 3 includes a suction chuck support 31 and a suction chuck 32 disposed on the suction chuck support 31. A workpiece is illustrated on a holding surface which is the upper surface of the suction chuck 32. Suction holding is performed by operating a suction means that does not. The chuck table 3 is configured to be rotatable by a rotation mechanism (not shown). The chuck table 3 is provided with a clamp 33 for fixing an annular frame that supports a wafer, which will be described later, as a work piece via a dicing tape. The chuck table 3 configured as described above can be moved in a machining feed direction (X-axis direction) indicated by an arrow X by a cutting feed means (not shown).

  A cutting apparatus 1 shown in FIG. 1 includes a spindle unit 4 as cutting means. The spindle unit 4 is disposed along an indexing feed direction (Y-axis direction) indicated by an arrow Y orthogonal to the machining feed direction (X-axis direction). The spindle unit 4 is moved in the index feed direction (Y-axis direction) by an index feed means (not shown), and is moved in the cut feed direction (Z-axis direction) indicated by an arrow Z in FIG. 1 by a not-shown cut feed means. It is like that. The spindle unit 4 is mounted on a moving base (not shown) and is adjusted to move in an indexing direction (Y-axis direction) and a cutting direction (Z-axis direction), and is rotatably supported by the spindle housing 41. A rotary spindle 42 and a cutting blade 43 attached to the front end of the rotary spindle 42 are provided. The rotary spindle 42 is configured to be rotated by a servo motor (not shown). The cutting blade 43 has a disk-shaped base 431 formed of aluminum, for example, as shown in FIG. 2, and diamond abrasive grains hardened by nickel plating on the outer peripheral side surface of the base 431 to a thickness of, for example, 50 μm. An annular cutting edge 432 is formed.

  A blade cover 44 that covers the upper half of the cutting blade 43 is attached to the front end of the spindle housing 41. The blade cover 44 includes a first cover member 441 mounted on the spindle housing 41 and a second cover member 442 mounted on the first cover member 441 in the illustrated embodiment. The first cover member 441 includes a front cover portion 441a formed with one end portion protruding toward the cutting blade 43 side. Further, a female screw hole 441b and two positioning pins 441c are provided on the side surface of the first cover member 441. The second cover member 442 has an insertion hole 442a at a position corresponding to the female screw hole 441b. Is provided. Further, on the surface of the second cover member 442 facing the first cover member 441, two recesses (not shown) into which the two positioning pins 441c are fitted are formed. The first cover member 441 and the second cover member 442 configured in this way are provided with two recesses (not shown) formed in the second cover member 442 provided in the first cover member 441. Positioning is performed by fitting to the positioning pin 441c. Then, the fastening bolt 443 is inserted into the insertion hole 442a of the second cover member 442, and is screwed into the female screw hole 441b provided in the first cover member 441, whereby the second cover member 442 is engaged with the first cover member 442. The cover member 441 is attached.

  Continuing the description with reference to FIG. 2, the cutting device 1 in the illustrated embodiment includes a cutting water supply mechanism 5 that supplies cutting water to a cutting portion by the annular cutting edge 432 of the cutting blade 43. Yes. The cutting water supply mechanism 5 includes a first cutting water supply pipe 511 and a second cutting water supply pipe 512 disposed on the first cover member 441 and the second cover member 442 constituting the blade cover 44. A cutting water supply means 52 for supplying cutting water to the first cutting water supply pipe 511 and the second cutting water supply pipe 512, and the first cutting water supply pipe 511 and the second cutting water. A first cutting water supply nozzle 531 and a second cutting water supply nozzle 532 connected to the supply pipe 512 are provided.

  The first cutting water supply pipe 511 and the second cutting water supply pipe 512 are respectively disposed on the first cover member 441 and the second cover member 442 constituting the blade cover 44, and the upper ends thereof are arranged. The first cutting water supply nozzle 531 and the second cutting water supply nozzle 532 are connected to the lower ends of the cutting water supply means 52 and the lower ends thereof, respectively.

  The cutting water feeding means 52 includes a pure water storage tank 521 for storing pure water for forming cutting water, an organic acid storage tank 522 for storing organic acid, and an oxidation for storing oxidant. An agent storage tank 523 and an anticorrosive agent storage tank 524 for storing the anticorrosive agent are provided. The pure water storage tank 521 stores pure water that has been conventionally used as cutting water.

The organic acid storage tank 522 stores amino acids, aminopolyacids, and carboxylic acids that can be used as organic acids.
Examples of amino acids that can be used as organic acids include glycine, dihydroxyethyl glycine, glycyl glycine, hydroxyethyl glycine, N-methyl glycine, β-alanine, L-alanine, L-2-aminobutyric acid, L-norvaline, L -Valine, L-leucine, L-norleucine, L-alloisoleucine, L-isoleucine, L-phenylalanine, L-proline, sarcosine, L-ornithine, L-lysine, taurine, L-serine, L-threonine, L- Allothreonine, L-homoserine, L-thyroxine, L-tyrosine, 3,5-diiodo-L-tyrosine, β- (3,4-dihydroxyphenyl) -L-alanine, 4-hydroxy-L-proline, L- Cysteine, L-methionine, L-ethionine, L-lanthionine, L-cysta Thionine, L-cystine, L-cysteic acid, L-glutamic acid, L-aspartic acid, S- (carboxymethyl) -L-cysteine, 4-aminobutyric acid, L-asparagine, L-glutamine, azaserine, L-canavanine, L-citrulline, L-arginine, δ-hydroxy-L-lysine, creatine, L-kynurenine, L-histidine, 1-methyl-L-histidine, 3-methyl-L-histidine, L-tryptophan, actinomycin C1, Examples include ergothioneine, apamin, angiotensin I, angiotensin II, and antipine. Of these, glycine, L-alanine, L-proline, L-histidine, L-lysine, and dihydroxyethylglycine are preferable.

  Examples of aminopolyacids that can be used as organic acids include iminodiacetic acid, nitrilotriacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminetetraacetic acid, hydroxyethyliminodiacetic acid, nitrilotrismethylenephosphonic acid, ethylenediamine-N, N, N ′, N'-tetramethylenesulfonic acid, 1,2-diaminopropanetetraacetic acid, glycol etherdiaminetetraacetic acid, transcyclohexanediaminetetraacetic acid, ethylenediamine orthohydroxyphenylacetic acid, ethylenediamine disuccinic acid (SS form), β-alanine diacetic acid, N -(2-carboxylate ethyl) -L-aspartic acid, N, N′-bis (2-hydroxybenzyl) ethylenediamine-N, N′-diacetic acid and the like.

  Examples of carboxylic acids that can be used as organic acids include formic acid, glycolic acid, propionic acid, acetic acid, butyric acid, valeric acid, hexanoic acid, oxalic acid, malonic acid, glutaric acid, adipic acid, malic acid, and succinic acid. , Pimelic acid, mercaptoacetic acid, glyoxylic acid, chloroacetic acid, pyruvic acid, acetoacetic acid, glutaric acid and other saturated carboxylic acids, acrylic acid, methacrylic acid, crotonic acid, fumaric acid, maleic acid, mesaconic acid, citraconic acid, aconite Examples include unsaturated carboxylic acids such as acids, cyclic unsaturated carboxylic acids such as benzoic acids, toluic acid, phthalic acids, naphthoic acids, pyrometic acid, and naphthalic acid.

  Examples of the oxidant stored in the oxidant storage tank 523 include hydrogen peroxide, peroxide, nitrate, iodate, periodate, hypochlorite, chlorite, chlorate, hydrogen peroxide, Use of chlorate, persulfate, dichromate, permanganate, cerate, vanadate, ozone water, silver (II) salt, iron (III) salt, organic complex salts thereof, etc. it can.

  The anticorrosive agent stored in the anticorrosive agent storage tank 524 includes a heteroaromatic ring compound having three or more nitrogen atoms in the molecule and a condensed ring structure, or four or more nitrogen atoms in the molecule. It is preferable to use a heteroaromatic ring compound having an atom. Furthermore, the aromatic ring compound preferably contains a carboxyl group, a sulfo group, a hydroxy group, or an alkoxy group. Specifically, tetrazole derivatives, 1,2,3-triazole derivatives, and 1,2,4-triazole derivatives are preferable.

  The tetrazole derivative that can be used as an anticorrosive agent has no substituent on the nitrogen atom forming the tetrazole ring, and a sulfo group, amino group, carbamoyl group, carbonamido group, sulfamoyl group at the 5-position of the tetrazole ring. A substituent selected from the group consisting of a group and a sulfonamide group, or a group selected from the group consisting of a hydroxy group, a carboxy group, a sulfo group, an amino group, a carbamoyl group, a carbonamido group, a sulfamoyl group, and a sulfonamide group In addition, an alkyl group substituted with at least one substituent is introduced.

  Moreover, as a 1,2,3-triazole derivative which can be used as an anticorrosive, it does not have a substituent on the nitrogen atom which forms a 1,2,3-triazole ring, and 1,2,3- A substituent selected from the group consisting of a hydroxy group, a carboxy group, a sulfo group, an amino group, a carbamoyl group, a carbonamido group, a sulfamoyl group, and a sulfonamide group at the 4-position and / or 5-position of the triazole; An alkyl group or an aryl group substituted with at least one substituent selected from the group consisting of a group, a carboxy group, a sulfo group, an amino group, a carbamoyl group, a carbonamido group, a sulfamoyl group, and a sulfonamido group was introduced Things.

  Furthermore, the 1,2,4-triazole derivative that can be used as an anticorrosive agent has no substituent on the nitrogen atom forming the 1,2,4-triazole ring, and 1,2,4- A substituent selected from the group consisting of a sulfo group, a carbamoyl group, a carbonamido group, a sulfamoyl group, and a sulfonamido group at the 2-position and / or 5-position of the triazole, or a hydroxy group, a carboxy group, a sulfo group, an amino group And an alkyl group or aryl group substituted with at least one substituent selected from the group consisting of a group, a carbamoyl group, a carbonamido group, a sulfamoyl group, and a sulfonamido group.

  Continuing the description with reference to FIG. 2, the pure water storage tank 521, the organic acid storage tank 522, the oxidant storage tank 523, and the anticorrosive storage tank 524 are respectively connected via electromagnetic open / close valves 521a, 522a, 523a, and 524a. And connected to the cutting water storage tank 525. The cutting water storage tank 525 stores the pure water storage tank 521, the organic acid storage tank 522, the oxidant storage tank 523, and the anticorrosive storage tank 524 by opening the electromagnetic on-off valves 521 a, 522 a, 523 a, and 524 a. Pure water, organic acid, oxidizer and anticorrosive are introduced. Note that the ratio of pure water, organic acid, oxidizing agent, and anticorrosive constituting the cutting water stored in the cutting water storage tank 525 is 50 cc of organic acid and oxidizer for 1000 cc of pure water in the illustrated embodiment. Is set to 20 cc, and the anticorrosive is set to 1 cc.

  The cutting water storage tank 525 for storing the cutting water composed of the pure water, the organic acid, the oxidizing agent, and the anticorrosive is the first cutting water supply pipe 511 via the cutting water supply pump 526 and the electromagnetic opening / closing valve 526a. And a second cutting water supply pipe 512. Therefore, by opening the electromagnetic on-off valve 526a and operating the cutting water supply pump 526, the cutting water stored in the cutting water storage tank 525 becomes the first cutting water supply pipe 511 and the second cutting water supply pipe 512. Then, the first cutting water supply nozzle 531 and the second cutting water supply nozzle 532 are supplied.

  The description will be continued with reference to FIG. 2. The illustrated cutting water supply means 52 is ejected from the first cutting water supply nozzle 531 and the second cutting water supply nozzle 532 by the cutting blade 432 of the cutting blade 43. A cutting water receiving container 527 that receives cutting water supplied to the cutting region, a cutting water return pump 528 that returns the cutting water received in the cutting water receiving container 527 to the cutting water storage tank 525, and the cutting water return pump 528 and the cutting water storage tank 525 are provided with a filter 529 disposed in a pipe. Therefore, by operating the cutting water return pump 528, the cutting water supplied to the cutting area by the cutting blade 432 of the cutting blade 43 and received by the cutting water receiving container 527 during the cutting operation is stored in the cutting water via the filter 529. Returned to tank 525. In this way, the cutting water stored in the cutting water storage tank 525 is circulated and used. When the water level of the cutting water stored in the cutting water storage tank 525 reaches a predetermined value or less, the electromagnetic open / close valves 521a, 522a, 523a, and 524a are opened, and the pure water storage tank 521 and the organic acid storage tank 522 are opened. Pure water, an organic acid, an oxidizing agent, and an anticorrosive agent are supplied from the oxidant storage tank 523 and the anticorrosive agent storage tank 524 to the cutting water storage tank 525 in a set amount.

  Returning to FIG. 1, the description continues and the cutting apparatus 1 in the illustrated embodiment images the surface of the workpiece held on the chuck table 3 and detects an area to be cut by the cutting blade 43. The image pickup means 7 is provided. The imaging means 7 is composed of optical means such as a microscope and a CCD camera. In addition, the cutting apparatus includes a display unit 8 that displays an image captured by the imaging unit 7.

  In the cassette mounting area 9a of the apparatus housing 2, a cassette mounting table 9 for mounting a cassette for storing a workpiece is disposed. This cassette mounting table 9 is configured to be movable in the vertical direction by a lifting means (not shown). On the cassette mounting table 9, a cassette 11 for storing a semiconductor wafer to be described later is mounted.

  Further, the cutting apparatus 1 in the illustrated embodiment includes a carry-out / carry-in means 13 for carrying out a semiconductor wafer (described later) accommodated in a cassette 11 placed on a cassette placement table 9 to a temporary placement table 12, and a temporary On the chuck table 3, a first transport means 14 for transporting the semiconductor wafer carried to the placing table 12 onto the chuck table 3, a cleaning means 15 for cleaning the semiconductor wafer cut on the chuck table 3, and There is provided second transport means 16 for transporting the cut semiconductor wafer to the cleaning means 15.

Next, a wafer processing method according to the present invention that is performed using the above-described cutting apparatus 1 will be described.
3A and 3B are a perspective view and an enlarged cross-sectional view of a main part of a semiconductor wafer processed by the wafer processing method according to the present invention. A semiconductor wafer 10 shown in FIGS. 3A and 3B has an inorganic film such as SiOF and BSG (SiOB), a polyimide film, a parylene film, etc. on the surface 100a of a semiconductor substrate 100 such as silicon having a thickness of 150 μm. A plurality of low-k insulating films made of organic film, which is a polymer film, and a low-k film 110 made of a laminated body in which metal foils such as copper and aluminum are entangled with each other in a lattice shape The devices 112 are formed in a plurality of regions partitioned by the scheduled division lines 111. Note that the thickness of the low-k film 110 is set to 10 μm in the illustrated embodiment.

A wafer processing method for dividing the semiconductor wafer 10 described above along the planned division line 111 to divide the Low-k film 110 to expose the semiconductor substrate 100 will be described.
First, a wafer support process is performed in which a dicing tape is attached to the back surface of the semiconductor substrate 100 constituting the semiconductor wafer 10 and the outer peripheral portion of the dicing tape is supported by an annular frame. That is, as shown in FIG. 4, the back surface 100b of the semiconductor substrate 100 constituting the semiconductor wafer 10 is bonded to the surface of the dicing tape T on which the outer peripheral portion is mounted so as to cover the inner opening of the annular frame F. Therefore, in the semiconductor wafer 10 adhered to the surface of the dicing tape T, the surface 110a of the low-k film 110 is on the upper side. Thus, the semiconductor wafer 10 supported by the annular frame F via the dicing tape T is accommodated in the cassette 11 and placed on the cassette placement table 9.

  The semiconductor wafer 10 (in a state supported by the annular frame F via the dicing tape T) accommodated in a predetermined position of the cassette 11 placed on the cassette placement table 9 is moved by the lifting means (not shown). The mounting table 9 is positioned at the carry-out position by moving up and down. Next, the carry-out / carry-in means 13 moves forward and backward to carry the semiconductor wafer 10 positioned at the carry-out position onto the temporary placement table 12. The semiconductor wafer 10 carried out to the temporary placement table 12 is transferred onto the chuck table 3 by the turning operation of the first transfer means 14.

  When the semiconductor wafer 10 is placed on the chuck table 3, suction means (not shown) is operated to suck and hold the semiconductor wafer 10 on the chuck table 3. An annular frame F that supports the semiconductor wafer 10 via the dicing tape T is fixed by the clamp 33. The chuck table 3 that sucks and holds the semiconductor wafer 10 in this way is moved to a position immediately below the imaging means 7. When the chuck table 3 is positioned immediately below the image pickup means 7, the image pickup means 7 detects the division line 111 formed on the semiconductor wafer 10, and moves and adjusts the spindle unit 4 in the arrow Y direction that is the indexing direction. Then, a precise alignment operation between the division line 111 and the cutting blade 43 is performed (alignment process).

  When the alignment step is performed as described above, the chuck table 3 is moved to the cutting region, and one end of the predetermined division line 111 is viewed from directly below the cutting blade 43 as shown in FIG. Position 5 (a) slightly to the right. When the semiconductor wafer 10 held on the chuck table 3 of the cutting apparatus 1 is positioned at the cutting start position in the cutting region in this way, the cutting blade 43 is indicated by a two-dot chain line in FIG. Cut from the standby position as indicated by an arrow Z1, and is positioned at a predetermined cut feed position as indicated by a solid line in FIG. This cutting feed position is a position where the lower end of the annular cutting edge 432 constituting the cutting blade 43 reaches the semiconductor substrate 100 constituting the semiconductor wafer 10 as shown in FIGS. 5 (a) and 5 (c). Is set.

  Next, the cutting blade 43 is rotated at a predetermined rotational speed in the direction indicated by the arrow 43a in FIG. 5A, and the chuck table 3 is rotated in the direction indicated by the arrow X1 in FIG. 5A. Move with. Then, when the chuck table 3 reaches the other end of the planned dividing line 111 (the right end in FIG. 5B) until it is positioned to the left by a predetermined amount from just below the cutting blade 43, as shown in FIG. The movement of the chuck table 3 is stopped. By processing and feeding the chuck table 3 in this manner, the low-k film 110 constituting the semiconductor wafer 10 is divided by the cutting grooves 130 formed along the planned division lines 111 as shown in FIG. Then, the semiconductor substrate 100 is exposed (Low-k film cutting step).

  Next, the cutting blade 43 is raised as shown by an arrow Z2 in FIG. 5B and positioned at a standby position shown by a two-dot chain line, and the chuck table 3 is moved in the direction shown by an arrow X2 in FIG. Move and return to the position shown in FIG. Then, the chuck table 3 is indexed and fed in the direction perpendicular to the paper surface (index feed direction) by an amount corresponding to the interval between the scheduled division lines 111, and the next divided division line 111 to be cut is placed at a position corresponding to the cutting blade 43. Position. Thus, if the division | segmentation scheduled line 111 which should be cut next is located in the position corresponding to the cutting blade 43, the Low-k film | membrane cutting process mentioned above will be implemented.

  When the Low-k film cutting process described above is performed, the electromagnetic open / close valve 526a constituting the cutting water feeding means 52 is opened and the cutting water supply pump 526 is operated to store in the cutting water storage tank 525. The cut water thus supplied is supplied to the first cutting water supply nozzle 531 and the second cutting water supply nozzle 532 via the first cutting water supply pipe 511 and the second cutting water supply pipe 512. As a result, as shown in FIG. 6, the organic acid is 50 cc, the oxidizing agent is 20 cc, and the anticorrosive is 1 cc with respect to 1000 cc of pure water from the first cutting water supply nozzle 531 and the second cutting water supply nozzle 532. The mixed cutting water is supplied to the cutting area of the cutting blade 43 by the cutting edge 432 at a rate of 2000 cc per minute. In this way, the cutting water in which pure water, organic acid, oxidizing agent, and anticorrosive agent are mixed is supplied to the cutting region by the cutting edge 432, so that the Low-k film 110 is configured by the oxidizing agent contained in the cutting water. In addition to the fact that the metal foil is modified and ductility is suppressed, the metal foil becomes brittle and the workability is accelerated by the organic acid, so that the low-k film 110 is cut without peeling. Moreover, corrosion (elution) of the metal foil constituting the Low-k film 110 is suppressed by mixing an anticorrosive into the cutting water. In addition, in the case of an electroformed blade or metal blade in which the cutting blade of the cutting blade is formed by solidifying diamond abrasive grains on the outer peripheral side surface of the base with nickel plating, the organic acid and the oxidizing agent are less than those of the vitrified blade and the resin blade. The mixed cutting water promotes the self-generated blade action, improves the cutting ability, and tends to suppress peeling of the Low-k film.

In addition, the said Low-k film | membrane cutting process is performed on the following process conditions, for example.
Cutting blade cutting edge: outer diameter 50 mm, thickness 50 μm
Cutting blade rotation speed: 20000 rpm
Cutting feed rate: 50 mm / sec Supply amount of cutting water: 2000 cc / min

  As described above, when the low-k film cutting process is performed along all the scheduled division lines 111 formed in the predetermined direction on the semiconductor wafer 10, the chuck table 3 holding the semiconductor wafer 10 is moved 90 degrees. Rotate. Then, the low-k film cutting process is performed along all the planned division lines 111 formed on the semiconductor wafer 10 in the direction orthogonal to the predetermined direction.

Next, another embodiment of the Low-k film cutting step will be described with reference to FIG.
In another embodiment of the Low-k film cutting step shown in FIG. 7, the semiconductor substrate in which the lower end of the annular cutting edge 432 constituting the cutting blade 43 constitutes the semiconductor wafer 10 as shown in FIG. It is positioned at a position reaching the dicing tape T to which the back surface of 100 is stuck. Accordingly, as in the Low-k film cutting process shown in FIG. 5, the chuck table 3 holding the semiconductor wafer 10 is processed and fed while rotating the cutting blade 43, so that the semiconductor as shown in FIG. The semiconductor substrate 100 together with the Low-k film 110 constituting the wafer 10 is cut by a cutting groove 131 formed along the planned dividing line 111. In this way, when the Low-k film cutting process is performed along all the division lines 111 formed in the predetermined direction on the semiconductor wafer 10, the chuck table 3 holding the semiconductor wafer 10 is rotated 90 degrees. Move. Then, the low-k film cutting process is performed along all the planned division lines 111 formed on the semiconductor wafer 10 in the direction orthogonal to the predetermined direction. As a result, the semiconductor wafer 10 is cut along the planned division line 111 and divided into individual devices.
In another embodiment of the Low-k film cutting step shown in FIG. 7, the cutting water feeding means 52 is operated to cut the cutting water mixed with pure water, organic acid, oxidizing agent and anticorrosive. 432 to the cutting area.

After the low-k film cutting step shown in FIG. 5 is performed, the semiconductor substrate 100 in which the low-k film 110 is divided and exposed along the planned division line 111 is cut along the planned division line 111. A cutting process is performed.
A first embodiment of this cutting step will be described with reference to FIG. The first embodiment of the cutting step shown in FIG. 8 can be performed using the cutting device 1 or a similar cutting device, but the thickness of the annular cutting edge 432a constituting the cutting blade 43 is the same. The annular cutting edge 432 constituting the cutting blade 43 that has performed the Low-k film cutting step is formed to have a thickness of, for example, 30 μm, which is thinner than the thickness (50 μm). Therefore, it demonstrates using the code | symbol of each structural member of the said cutting device 1 except the cyclic | annular cutting edge 432a.

  In order to implement the first embodiment of the cutting process, the semiconductor wafer 10 on which the Low-k film cutting process shown in FIG. 5 is performed is sucked and held on the chuck table 3 through the dicing tape T as described above. To do. The chuck table 3 that sucks and holds the semiconductor wafer 10 in this way is moved to a position immediately below the imaging means 7. When the chuck table 3 is positioned immediately below the image pickup means 7, the image pickup means 7 detects the cutting groove 130 formed along the planned division line 111 formed in the semiconductor wafer 10, and the spindle unit 4 is indexed. Then, a precise alignment operation between the cutting groove 130 and the cutting blade 43 is performed by adjusting the movement in the arrow Y direction (alignment process).

  When the alignment step is performed as described above, the chuck table 3 is moved to the cutting region, and the cutting grooves 130 formed along the predetermined division line 111 as shown in FIG. One end is positioned slightly to the right in FIG. 8A from directly below the cutting blade 43. If the semiconductor wafer 10 held on the chuck table 3 is positioned at the cutting start position in the cutting region in this way, the cutting blade 43 is moved from the standby position indicated by the two-dot chain line in FIG. As shown by Z1, the sheet is cut and fed downward, and is positioned at a predetermined cutting and feeding position as shown by a solid line in FIG. As shown in FIGS. 8A and 8C, the cutting feed position is such that the lower end of the annular cutting edge 432a constituting the cutting blade 43 is attached to the back surface of the semiconductor substrate 100 constituting the semiconductor wafer 10. It is set at a position that reaches the dicing tape T that is being worn.

  Next, the cutting blade 43 is rotated at a predetermined rotational speed in the direction indicated by an arrow 43a in FIG. 8A, and the chuck table 3 is rotated in a direction indicated by an arrow X1 in FIG. 8A. Move with. Then, the other end (the right end in FIG. 8B) of the cutting groove 130 in which the chuck table 3 is formed along the scheduled dividing line 111 as shown in FIG. 8B is located immediately below the cutting blade 43. When reaching the fixed amount left side, the movement of the chuck table 3 is stopped. By processing and feeding the chuck table 3 in this way, the semiconductor substrate 100 constituting the semiconductor wafer 10 is formed along the cutting groove 130 formed along the planned division line 111 as shown in FIG. The cutting groove 132 is cut (cutting step). In this cutting step, pure water may be used as the cutting water supplied to the cutting area by the cutting edge 432a.

  Next, the cutting blade 43 is raised as shown by the arrow Z2 in FIG. 8B and positioned at the standby position shown by the two-dot chain line, and the chuck table 41 is moved in the direction shown by the arrow X2 in FIG. Move and return to the position shown in FIG. Then, the chuck table 3 is indexed and fed in the direction perpendicular to the paper surface (index feed direction) by an amount corresponding to the interval between the scheduled division lines 111, and the cutting groove 130 formed along the scheduled division line 111 to be cut next. Is positioned at a position corresponding to the cutting blade 43. Thus, if the cutting groove 130 formed along the scheduled division line 111 to be cut next is positioned at a position corresponding to the cutting blade 43, the above-described cutting process is performed. In this way, if the above-described cutting process is performed along the cutting grooves 130 formed along all the planned dividing lines 111 formed in the predetermined direction on the semiconductor wafer 10, the chuck table holding the semiconductor wafer 10. 3 is rotated 90 degrees. Then, the cutting process is performed along the cutting grooves 130 formed along all the planned division lines 111 formed in the semiconductor wafer 10 in the direction orthogonal to the predetermined direction. As a result, the semiconductor wafer 10 is cut along the planned division line 111 and divided into individual devices.

  Next, a second embodiment of the cutting process will be described with reference to FIGS. The second embodiment of this cutting step is performed using a laser processing apparatus 60 shown in FIG. A laser processing apparatus 60 shown in FIG. 9 includes a chuck table 61 that holds a workpiece, laser beam irradiation means 62 that irradiates a workpiece held on the chuck table 61 with a laser beam, and a chuck table 61 that holds the workpiece. An image pickup means 63 for picking up an image of the processed workpiece is provided. The chuck table 61 is configured to suck and hold the workpiece. The chuck table 61 is moved in a processing feed direction indicated by an arrow X in FIG. 9 by a processing feed means (not shown), and in FIG. 9 by an index feed means (not shown). It can be moved in the index feed direction indicated by the arrow Y.

  The laser beam irradiation means 62 includes a cylindrical casing 621 disposed substantially horizontally. In the casing 621, a pulsed laser beam oscillation means including a pulsed laser beam oscillator and a repetition frequency setting means (not shown) are arranged. A condenser 622 for condensing the pulse laser beam oscillated from the pulse laser beam oscillating means is attached to the tip of the casing 621. The laser beam irradiating unit 62 includes a condensing point position adjusting unit (not shown) for adjusting the condensing point position of the pulse laser beam collected by the condenser 622.

  The imaging means 63 attached to the tip of the casing 621 constituting the laser beam irradiation means 62 includes an illumination means for illuminating the workpiece, an optical system for capturing an area illuminated by the illumination means, and the optical system. An image pickup device (CCD) or the like for picking up the captured image is provided, and the picked-up image signal is sent to a control means (not shown).

  In order to implement the second embodiment of the cutting process using the laser processing apparatus 60 described above, the dicing tape T side of the semiconductor wafer 10 on which the Low-k film cutting process shown in FIG. 61 is mounted. By operating a suction means (not shown), the semiconductor wafer 10 is sucked and held on the chuck table 61 via the dicing tape T (wafer holding step). In FIG. 9, the annular frame F to which the dicing tape T is attached is omitted, but the annular frame F is held by appropriate frame holding means provided on the chuck table 61. In this way, the chuck table 61 that sucks and holds the semiconductor wafer 10 is positioned directly below the imaging unit 63 by a processing feed unit (not shown).

  When the chuck table 61 is positioned immediately below the image pickup means 63, an alignment operation for detecting a processing region to be laser processed of the semiconductor wafer 10 is executed by the image pickup means 63 and a control means (not shown). That is, the imaging unit 63 and a control unit (not shown) are configured to cut the cutting groove 130 formed along the predetermined division line 111 formed in the predetermined direction of the semiconductor wafer 10 and the laser beam that irradiates the laser beam along the cutting groove 130. Image processing such as pattern matching for performing alignment with the condenser 622 of the irradiation unit 62 is performed, and alignment of the laser beam irradiation position is performed (alignment process). In addition, the alignment of the laser beam irradiation position is similarly performed on the cutting groove 130 formed along the planned dividing line 111 formed in the semiconductor wafer 10 in a direction orthogonal to the predetermined direction.

  When the alignment step described above is performed, the chuck table 61 is moved to the laser beam irradiation region where the condenser 622 of the laser beam irradiation means 62 for irradiating the laser beam is located as shown in FIG. As shown, one end of the cutting groove 130 formed along a predetermined division line 111 formed in the semiconductor wafer 10 (left end in FIG. 10A) is positioned so as to be located immediately below the condenser 622. . Next, the chuck table 61 is applied to the semiconductor substrate 100 constituting the semiconductor wafer 10 from the condenser 622 of the laser beam irradiation means 62 while irradiating a pulsed laser beam having an absorptive wavelength or a transmissive wavelength as shown in FIG. In (a), it is moved at a predetermined processing feed speed in the direction indicated by the arrow X1 (laser processing step). Then, when the other end of the cutting groove 130 formed along the planned division line 111 as shown in FIG. 10B (the right end in FIG. 10B) reaches a position directly below the condenser 622, The irradiation of the pulse laser beam is stopped and the movement of the chuck table 61 is stopped.

  By performing the above-described laser processing step, the semiconductor substrate 100 constituting the semiconductor wafer 10 is formed along the cutting groove 130 formed along the division line 111 as shown in FIGS. 10 (c) and 10 (d). It is cut by the laser processed groove 133 or the modified layer 134 formed in this manner. By performing this laser processing step along the cutting grooves 130 formed along all the division lines 111 formed on the semiconductor wafer 10, the semiconductor wafer 10 is cut along the division lines 111 to be individually separated. Divided into devices.

2: Device housing 3: Chuck table 4: Spindle unit 43: Cutting blade 44: Blade cover 5: Cutting water supply mechanism 511: First cutting water supply pipe 512: Second cutting water supply pipe 52: Cutting water feed Means 531: First cutting water supply nozzle 532: Second cutting water supply nozzle 7: Imaging means 10: Semiconductor wafer 100: Semiconductor substrate 110: Low-k film length 11: Cassette 12: Temporary placement table 13: Unloading Carry-in means 14: First transport means 15: Cleaning means 16: Second transport means 60: Laser processing device 61: Chuck table 62 of laser processing device: Laser beam irradiation means 622: Condenser
F: Annular support frame
T: Dicing tape

Claims (4)

A wafer processing method in which devices are formed in a plurality of regions defined by a plurality of division lines formed in a lattice pattern in a low-k film stacked on the surface of a semiconductor substrate,
A wafer holding step for holding the back side of the wafer in the workpiece holding means of the cutting device;
A cutting blade having a cutting edge on the outer periphery is positioned on a scheduled division line of the wafer held by the workpiece holding means, and a high-speed rotating cutting blade is positioned, and the workpiece holding means and the cutting blade are relatively processed and fed. A low-k film cutting step that divides at least the low-k film along the planned dividing line,
In the Low-k film cutting step, cutting water containing an organic acid and an oxidizing agent is supplied to a cutting region by the cutting blade of the cutting blade.
A method for processing a wafer.   The wafer processing method according to claim 1, wherein an anticorrosive agent is mixed in the cutting water.   3. The wafer processing method according to claim 1, wherein the low-k film cutting step cuts the semiconductor substrate together with the low-k film along a line to be divided.   3. The cutting step of cutting the semiconductor substrate exposed along the planned division line after the low-k film cutting step is cut along the planned division line. The processing method of the wafer as described.