JP4690263B2 - Wafer backside grinding method and apparatus - Google Patents

Description

  The present invention relates to a back grinding method and apparatus for effectively using a silicon fine particle-containing liquid (slurry or sludge) generated by wafer back grinding.

  As represented by mobile portable personal computers and mobile phones, electronic devices are rapidly increasing in performance, size and weight. Under such a trend, there is a demand for higher performance and miniaturization of semiconductor devices, and recently, semiconductor devices in which many thin IC chips are stacked have appeared.

  On the other hand, in the semiconductor industry, very intense cost competition is taking place, and the wafer diameter is rapidly increasing. As the wafer diameter increases, handling becomes difficult, and the thickness of the wafer inevitably increases. For example, in the case of a wafer having a diameter of about 30 cm (12 inches), the thickness is 700 to 800 microns. It is about a meter. On the other hand, the thickness of one IC chip used for the multi-layered semiconductor device of the IC chips is required to be about 30 to 150 microns / m. The backside grinding of the semiconductor process completed wafer is performed so that it can be provided.

  Also, with the rapid growth of the solar cell industry over the past few years, the demand for silicon, which is a raw material for wafers, has increased rapidly, and the demand continues to greatly exceed the supply of raw material silicon. In the above-mentioned backside grinding, silicon fine particles of about 1 micrometer / meter are suspended and discharged in a slurry form in pure water that is supplied in large quantities during grinding (or as a slightly viscous mud sludge. At present, the method for collecting silicon fine particles from that state has not been established, and is currently disposed of as industrial waste.

Therefore, the inventors have invented a method of recovering silicon fine particles from slurry (or sludge) silicon-containing waste liquid, but the silicon fine particles obtained from the back surface grinding of the semiconductor substrate include impurities formed during the semiconductor process. Impurity-containing silicon fine particles derived from the inclusion layer (for example, P-Si [poly-silicon] layer formed on the entire outer surface including both front and back surfaces of the semiconductor substrate by low pressure CVD) are mixed into pure silicon fine particles and used as silicon raw materials as they are There was a problem that I could not do. Incidentally, as a wafer back grinding apparatus, there is an apparatus such as JP-A-2000-269175. However, the impurity-containing silicon fine particles derived from the above-mentioned impurities cannot be separated from the pure silicon fine particles, and generated by this apparatus. The silicon-containing waste liquid such as slurry was inevitably discarded as industrial waste.
JP 2000-269175 A

  An object of the present invention is to provide a wafer backside grinding method and an apparatus therefor that enable the recovery of pure silicon fine particles, which is impossible with the conventional backside grinding.

The invention according to claim 1 is a method of grinding a back surface of a wafer according to the present invention.
(a) In the integrated circuit pattern forming process of forming an integrated circuit pattern on the front surface, the back surface of the wafer (S) on which the impurity layer (sf) is laminated on the back surface is ground to remove at least the impurity layer (sf),
(b) Impurity layer removal Performs impurity removal cleaning of the wafer (S) after backside grinding,
(c) The back surface of the wafer (S) after the impurity cleaning is ground while supplying pure water so that the wafer (S) has a predetermined thickness and silicon fine particles generated by the grinding are collected together with pure water. After
(d) The back surface of the wafer (S) is finish-ground.

The invention according to claim 2 relates to an apparatus for carrying out the method,
(a) Wafer supply mechanism unit (1) for receiving wafers (S) one by one after the semiconductor process is completed and the impurity layer (sf) is formed on the entire outer surface of the wafer (S), and the wafer supply mechanism unit A wafer back grinding device (A) composed of a wafer back grinding device section (2) for grinding the back surface of the wafer (S) supplied from (1),
(b) Wafer back grinding unit (2) is divided into 4 categories: wafer receiving zone (z1), back surface impurity layer removal zone (z2), back rough grinding zone (z3) and back surface finishing grinding zone (z4). And
(b1) At least four wafer chuck mechanism portions (41) to (44) provided at equal intervals, and the wafer chuck mechanism portions (41) to (44) in each zone (z1 to 4) in order. A turntable (3) for intermittent patrol,
(b2) At the stop position of the turntable (3) other than the wafer receiving zone (z1), the wafer (S) at each stop position is provided at a position facing the wafer chuck mechanism (42) to (44). Back surface impurity layer removal grinding mechanism part (52) for performing predetermined grinding on the back surface of the back surface rough grinding mechanism part (53) and back surface finishing grinding mechanism part (54),
(b3) When the turntable (3) is stopped, it is inserted under the wafer chuck mechanism (42) to (44) at the stop position of the turntable (3) other than the wafer receiving zone (z1), and back grinding A recovery tray mechanism (62) to (64) or (62 ′) to (64 ′) for recovering the silicon fine particle-containing liquid generated by
(b4) At the stop position of the turntable (3) other than the wafer receiving zone (z1), supply pure water to the wafer (S) chucked by the wafer chuck mechanism (42) to (44) during grinding, At least in the back surface impurity layer removal grinding mechanism part (52), pure water supply nozzles (72) to (74) for supplying pure water even after the completion of grinding to wash and remove the impurity-containing silicon fine particle-containing liquid after grinding; It is characterized by comprising.

  Claim 3 (FIG. 8) relates to one embodiment of the recovery tray mechanism parts (62 ′) to (64 ′) of the wafer back grinding apparatus (A) according to claim 2, and “for recovering silicon fine particle-containing liquid”. The moving recovery tray sections (62c) to (64c) of the recovery tray mechanism sections (62 ') to (64') are chuck mechanism sections (42) to (44) for chucking the wafer (S) for grinding. The turntable (3) is inserted under the chucking tables (42a) to (44a) when the turntable (3) is stopped so as to surround the chucking tables (42a) to (44a). It is sometimes controlled to be detached from each chuck mechanism (42) to (44) ".

Claim 4 (FIGS. 3 to 7) relates to another embodiment of the recovery tray mechanism parts (62) to (64) of the wafer back grinding apparatus (A) according to claim 2, and “for collecting silicon fine particle-containing liquid”. The collection tray sets (62a) to (64a) of the collection tray mechanism sections (62) to (64) of
(1) The chuck mechanism portions (42) to (44) are fixed below the chucking tables (42a) to (44a) so as to surround the chucking tables (42a) to (44a). Table side fixed collection tray part (62a1) ~ (64a1),
(2) Inserted between the table-side fixed collection trays (62a1) to (64a1) and the chucking tables (42a) to (44a) when the turntable (3) is stopped, and the turntable (3) Moving collection tray sections (62a2) to (64a2) controlled to be detached from the respective chucking tables (42a) to (44a) during movement,
(3) Fixed to the base plate (20) side of the wafer back grinding unit (2), and at least one of the table-side fixed collection trays (62a1) to (64a1) and the moving collection trays (62a2) to (64a2) It is composed of base plate side fixed collection trays (62a3) to (64a3) for collecting the silicon fine particle-containing liquid ground from one side. "

  As described above, the present invention removes the impurity layer (sf) formed on the back surface of the wafer (S) in advance by the impurity layer removal back surface grinding before the rough grinding, and subsequently performs the impurity layer removal back surface grinding. The chucking tables (42a) to (44a) of the collected tray mechanism units (62) to (64) or (62 ') to (64') and the chuck mechanism units (42) to (44) including the finished wafer (S) The silicon fine particles produced by the subsequent rough grinding of the back surface are almost free of impurities, and by separating the water, high purity as a silicon raw material is obtained. Silicon fine particles can be obtained.

  Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 is a plan view of a wafer back grinding apparatus (A) showing an embodiment of the present invention, and FIG. 2 is a perspective view of the apparatus (A). This apparatus (A) can be broadly divided into (a) a wafer supply mechanism section (1) for receiving wafers (S) after completion of the semiconductor process one by one, and a wafer (S) supplied from the wafer supply mechanism section (1). ) Is a wafer back surface grinding device composed of a wafer back surface grinding device section (2), and the substrate (10) stretched on the wafer supply mechanism section (1) Wafer loading cassettes (11a) and (11b) are arranged in a front row as a pair, the wafer loading cassette (12) is behind the left wafer loading cassette (11a), and the wafer cleaning is performed at the rear of the right cassette (11b). The mechanism (13) is arranged as a pair, and the base plate (20) of the wafer back grinding device (2) is drilled in the center of the back of the wafer temporary table (12) and the wafer cleaning mechanism (13). Installed so that the index turntable (3) rotates intermittently clockwise. Ri is further erected robot hand mechanism (8) is in front of the intermediate with and index the turntable of the wafer provisional table (12) and the wafer cleaning mechanism (13) (3).

  Wafer loading cassettes (11a) and (11b) are existing, have the same shape and are compatible, and have multiple horizontal step grooves in the frame (11f). Alternatively, the processed wafer (S) is stored, and can be transferred from the previous process to the apparatus (A) in the stored state or to the next process in the stored state. Is.

  The robot hand mechanism unit (8) includes an elevation mechanism unit (8a), a rotation drive mechanism unit (8b), a wafer alignment measurement mechanism unit (8c), an arm mechanism unit (8d) composed of one or more arms, and a tip. Vacuum tweezers (8e) attached to the tip of the arm (8d1), an articulated robot composed of these arm mechanism (8d) and a drive control mechanism (not shown) for the vacuum tweezers (8e), The wafer (S) on the wafer temporary table (12) can be transferred to the chuck mechanism (41) located in the wafer receiving zone (z1) of the index turntable (3), and on the cleaning mechanism (13). The wafer (S) is transferred to the wafer unloading cassette (11b).

  The vacuum tweezers (8e) has a plurality of suction holes (not shown) for sucking and detaching the wafer (S) on the tip surface of the tip bifurcated portion (8f). An air passage (not shown) communicating with the suction hole is provided inside the vacuum tweezers (8e). The diameter of the vacuum tweezers (8e) is 2/3 to 4/3, preferably about the same diameter as the wafer diameter.

  The arm mechanism portion (8d) is connected to be able to bend and stretch at the joint portion including the tip arm (8d1), and the bending and stretching angle is controlled by a driving source such as a stepping motor.

  The elevating mechanism (8a) is for elevating and lowering the arm mechanism (8d) installed thereon, and the arm mechanism (8d) can be raised and stopped at an arbitrary position, for example The driving source is something like a cylinder.

  The rotation drive mechanism (8b) rotates the elevating mechanism (8a) and the arm mechanism (8d) installed on the rotation drive mechanism (8b) in a 360 ° horizontal plane. For example, a drive source such as a stepping motor is provided. The rotation angle is controlled by.

  The temporary wafer mounting table (12) moves the wafer (S) taken out from the wafer loading cassette (11a) to the chuck mechanism (41) located in the wafer receiving zone (z1) of the index turntable (3). The base plate (20) of the index turntable (3) in the vicinity thereof is provided with a transfer arm (15) that can be swung freely and raised and lowered, and a transfer vacuum tweezer (15a ) Is provided, and the transfer vacuum tweezers (15a) conveys the wafer (S) from the temporary wafer holder (12) to the chuck mechanism (41) located in the wafer receiving zone (z1). Yes.

  The index turntable (3) is provided at the center of the base plate (20) of the wafer back grinding unit (2) by a spindle drive motor (3a) so that it can rotate 90 ° in one direction. Four wafer chuck mechanism portions (41) to (44) are arranged at equal intervals of 90 ° on concentric circles with respect to the rotation center of 3). Then, the recovery tray mechanism parts (62) to (64) or (62 ') to (64') and the back surface impurity layer removal grinding mechanism part (corresponding to the wafer chuck mechanism parts (42) to (44) in these ( 52), a back rough grinding mechanism (53), a back finishing grinding mechanism (54), and the like. The space above the index turntable (3) is divided into four sections according to its function: a wafer receiving zone (z1), a back surface impurity layer removal zone (z2), a back surface rough grinding zone (z3), and a back surface finish grinding zone (z4). The wafer chuck mechanism portions (41) to (44) sequentially move in the zones by the 90 ° intermittent rotation of the index turntable (3).

  Hereinafter, the wafer chuck mechanism (41) to (44), the recovery tray mechanism (62) to (64), and the back surface grinding mechanism (52) to (54) will be described. Therefore, the rough grinding zone (z3) will be described as a representative example (see FIGS. 3 to 7). In the drawings, the same members are distinguished by putting 1-4 as the second number.

  In FIG. 6, the chucking table (43a) of the wafer chuck mechanism (43) is rotated by a planetary rotation drive motor (43d), and there are many chucking tables (43a) on the surface of the chucking table (43a). The suction hole (43b) is formed, and the wafer (S) placed upside down on the suction hole (43b) is sucked and fixed. The chucking table (43a) is lifted from the turntable (3) by the rotating shaft (43c) of the planetary rotation drive motor (43d), and the collection tray is inserted into and removed from the turntable (3). A clearance (K) is provided. One or more pure water supply nozzles (73) are provided above the chucking table (43a) at appropriate positions.

  In FIG. 2, frames (21a) and (21b) are erected from the left side to the rear row toward the index turntable (3), and a wafer grinding mechanism ( 52) to (54) are attached, and the spindle shaft of the grinding motor (53M) [(52M) (54M)] of the wafer grinding mechanism (53) [(52) (54)] as shown in FIG. 53a) [(52a) (54a)] is mounted with a diamond grindstone (53c) [(52c) (54c)] suitable for each zone (z1) (z2) (z3) (z4).

  The recovery tray mechanism parts (62) to (64) shown in FIGS. 3 to 5 are provided in the grinding mechanism parts (52) to (54) excluding the wafer receiving zone (z1). The collection tray set (63a) of the collection tray mechanism section (63) for grinding is provided under the chucking table (43a) avoiding the table side fixed collection tray section (63a1) and the chucking table (43a). It is composed of a moving recovery tray section (63a2) in the form of a dish having an upper surface opening inserted into and removed from the gap (K) and a base plate side fixed recovery tray section (63a3) fixed to the base plate (20) side.

  The table-side fixed collection tray section (63a1) has a flat dish shape at the top opening, is fixed to the turntable (3), and rotates together with the turntable (3). Its shape is composed of a fixed floor member (63a12) through which the rotating shaft (43c) passes, and a fixed wall member (63a13) that covers three surfaces excluding the outer peripheral side edge of the turntable (3). The turntable (3) has an open portion at the outer peripheral side edge, and a tongue piece (63a16) is suspended from this portion, and an open portion (63a11) for flowing out the recovered silicon fine particle-containing liquid. It has become. The fixed floor member (63a12) is provided with a partition wall (63a14) that surrounds the rotating shaft (43c) and prevents the collected silicon fine particle-containing liquid from flowing into the rotating shaft (43c). .

  The moving collection tray part (63a2) is also in the shape of a dish with an upper opening, and a cutout groove (63a21) is formed in the bottom part (63a24) up to the insertion tip in the insertion / removal direction in order to avoid the chucking table (43a). An inner wall portion (63a22) is erected so as to cover the side surface and the outer peripheral portion so as not to interfere with the chucking table (43a), and the outer wall portion (63a23) is provided on the remaining outer peripheral portion of the bottom portion (63a24). ) And a slide arm (63a24) projecting rearward on the back, and moving and collecting in the advancing / retracting / removing direction by the tray drive unit (63d) provided on the side of the device (A) The tray section (63a2) is driven. The silicon fine particle-containing liquid recovered by the moving recovery tray part (63a2) is discharged to the base plate side fixed recovery tray part (63a3) described later through the drain hole (63b) of the floor part (63a24).

  The base plate side fixed collection tray section (63a3) is also a dish-shaped member having an upper surface opening, and is fixed to the base plate (20) side. A side wall (63a32) is erected around the bottom (63a31), and a drainage pipe (63a33) is provided on the bottom (63a31) to collect and collect the collected silicon fine particle-containing liquid. It is like that. The front side wall portion (63a33) is formed in a concave arc shape so as not to interfere with the outer periphery of the turntable (3), and further, the tongue of the open portion (63a11) is provided so as not to interfere with the open portion (63a11). A cutout (63a34) is provided to avoid the piece (63a16).

  As shown in FIG. 9, the wafer cleaning mechanism (13) includes a petal-like wafer support auxiliary frame (13c) supported by a hollow shaft (13a) that can be moved up and down in the vertical direction, and the auxiliary frame (13c). Porous ceramic plate (13b) fitted in the petal portion of the wafer, a plurality of wafer alignment pins (13d) arranged in such a manner that the interval between the petal portions can be expanded and contracted, and rinse (pure water supply) ) The nozzle (13e) and the air supply nozzle (13f) are roughly configured. The cleaning side swing arm (16) is swingably provided on the base plate (20) in the vicinity of the wafer cleaning mechanism (13), and the cleaning side transfer vacuum tweezers (16a) is installed at the tip. Has been.

  Pure water is oozed from the porous ceramic plates (13b) (13b) of the wafer support auxiliary frame (13c) to float the wafer (S), and the wafer (S) is sprayed with pure water from the rinse nozzle (13e) on the wafer surface. ) Clean both front and back. After the cleaning is finished, the leaching of pure water and the spraying of pure water are stopped. After that, the outer periphery of the wafer (S) is arranged by a plurality of pins (13d) arranged around the wafer (S) and moving in the direction of diameter reduction Press to perform centering (positioning). Subsequently, the wafer (S) is rotated by raising and rotating the hollow shaft (13a), and air is blown from the air supply nozzle (13f) to the wafer (S) while rotating the wafer (S). Dry and wait for transfer to storage cassette (11b).

  Next, using the grinding apparatus (A), the back surface of the wafer (S) is ground by the following process. One wafer (S) is adsorbed and taken out from the wafer loading cassette (11a) by the vacuum tweezers (8e) of the articulated robot hand mechanism (8), and this is placed on the temporary wafer table (12). During this time, the turntable (3) is rotated by 90 degrees, and the wafer chuck mechanism (41) after empty (or back-ground ground wafer (S) has been transferred to the storage cassette (11b)) is received by the wafer. Located in zone (z1).

  Next, the transfer vacuum tweezers (15a) sucks the wafer (S) on the temporary wafer mounting table (12), and the transfer vacuum tweezers (15a) is swung to turn the suction wafer (S) to the turntable. The wafer is transferred to the wafer chuck mechanism (41) located in the wafer receiving zone (z1) of (3). Meanwhile, the wafer (S) of the wafer loading cassette (11a) is adsorbed by the vacuum tweezers (8e) of the articulated robot hand mechanism (8), and this is placed on the temporary wafer table (12). Wait for the transfer. When there is a ground wafer (S) in the zone (z1), at the same time, a cassette (11b) of the ground wafer (S) is removed from the wafer cleaning mechanism (13) by the vacuum tweezers (16a) for transfer on the cleaning side. ).

  When the transfer is completed, the turntable (3) is rotated 90 degrees, and the wafer chuck mechanism (41) on which the wafer (S) is sucked and mounted is moved to the impurity layer grinding / removal zone (z2). When this zone (z2) is entered, the reference (41) of the wafer chuck mechanism is (42) in accordance with the work performed there. Since the description here is made in accordance with FIGS. 3 to 5 which are drawings of the next zone (z3), the second number 3 is replaced with 2.

  3-5, before or simultaneously with the movement, the tray drive section (63d) is operated to move the movement collection tray section (62a2) forward, and the chuck of the wafer chuck mechanism section (42) located in this zone (z2) is moved. Insert into the gap (K) below the king table (42a). In this state, the first spindle shaft (52a) is lowered to press the diamond grindstone (52c) against the back surface of the wafer (S), and the wafer chuck mechanism unit is supplied with pure water from the pure water supply nozzle (72). The chucking table (42a) of (42) and the first spindle shaft (52a) are rotated to grind away the impurity layer (sf) formed and deposited on the back surface of the wafer (S). In this case, since it is necessary to completely remove the impurity layer (sf), the silicon layer (st) of the wafer (S) may be slightly etched. As can be seen from the enlarged view of FIG. 6, the impurity layer (sf) is also formed on the side surface of the wafer (S). However, since this portion is very small in quantity, The grinding removal to the impurity layer (sf) is not performed.

  The ground impurity layer (sf) becomes fine particles with an average particle size of about 1 micron · meter and flows into the table-side fixed collection tray section (62a1) and mobile collection tray section (62a2) together with the supplied pure water. Then, they further flow into the base plate side fixed collection tray section (62a3), are collected through the drain pipe (62a33), and are discarded as industrial waste.

  When the removal of the impurity layer (sf) is finished, the diamond grindstone (52c) for back surface impurity layer removal grinding is raised, and the chucking table (42a) of the wafer chuck mechanism part (42) located in the same zone (z2) The pure water is continuously supplied while rotating the table, and the table-side fixed collection tray section (62a1), the chucking table (42a) and the wafer (S) adsorbed and fixed thereon are cleaned. These waste liquids are also discharged. The cleaning at this point prevents the removed impurities from being carried over to the next step (z3), as well as the wafer (S), as well as the chucking table (42a) and the table-side fixed collection tray (62a1). Perform cleaning. When the cleaning is completed, the rotation of the chucking table (42a) and the supply of pure water are stopped, and then the moving collection tray part (62a2) is retracted and detached from the chucking table (42a).

  During this period, the wafer (S) waiting on the wafer temporary table (12) is emptied (or as described above) in the wafer receiving zone (z1) of the turntable (3) with the vacuum tweezers (15a) for transfer. And the next wafer (S) in the wafer loading cassette (11a) is temporarily transferred to the wafer chuck mechanism (41) and transferred to the wafer loading cassette (11a) using the articulated robot hand mechanism (8) as described above. Place on the table (12) and wait for the next transfer. As described above, when there is a ground wafer (S) in the zone (z1), at the same time, the cleaning side transfer vacuum tweezers (16a) removes the ground wafer (S) from the wafer cleaning mechanism (13). Accommodation in the cassette (11b) is performed.

  When the transfer is completed, the turntable (3) is then rotated 90 degrees to move the wafer chuck mechanism (42) to the rough grinding zone (z3), and the wafer chuck mechanism (42) is moved to the rough grinding zone (z3). ) To stop. The wafer chuck mechanism (42) stopped in the zone (z3) is set to (43) according to the work contents there. In the zone (z3), as performed in the impurity layer removal zone (z2), the moving recovery tray unit (63a2) for recovering the liquid containing the coarsely ground silicon fine particles is moved forward in the main zone (before or simultaneously with the movement). Insert into the gap (K) below the chucking table (43a) of the wafer chuck mechanism (43) of z3). In this state, the second spindle shaft (53a) is lowered to press the diamond grindstone (53c) against the back surface of the wafer (S), and the wafer chuck mechanism unit is supplied with pure water from the pure water supply nozzle (73). The chucking table (43a) of (43) and the second spindle shaft (53a) are rotated to grind and remove the back surface of the wafer (S) by a predetermined amount.

  At this point, since the pure silicon layer (st) is exposed on the back surface of the wafer (S), the ground silicon fine particles are pure silicon that can be used as a silicon raw material, and have the required thickness. Grind to the front. Incidentally, a very small amount of carbon constituting the diamond grindstone (53c) is contained as an impurity. The ground pure silicon fine particles are fine particles with an average particle size of about 1 micron · meter and become slurry with a large amount of pure water supplied during rough grinding, as described above, and the table side fixed recovery tray (63a1) and moving recovery tray It flows into the base plate side fixed collection tray section (63a3) through the section (63a2) and is collected through the drain pipe (63a33).

  When the rough grinding is completed, the diamond grinding wheel (53c) for rough grinding is raised as described above, and pure water is supplied while rotating the chucking table (43a) of the wafer chuck mechanism (43) located in the same zone (z3). The supply is continued, and the chucking table (43a), the wafer (S) sucked and fixed on the chucking table (43a), and the table side fixed collection tray section (63a1) are cleaned. When the cleaning is completed, the rotation of the chucking table (43a) and the supply of pure water are stopped, and then the moving collection tray part (63a2) is retracted and detached from the chucking table (43a). Here, unlike the backside impurity layer removal grinding, it is not necessary to clean completely, so that the cleaning can be completed simultaneously with the completion of grinding.

  During the same period as before, the impurity layer is removed by grinding in the impurity layer removal zone (z2), the wafer (S) is supplied in the wafer collection zone (z1), and the wafer loading cassette (11a) to the wafer temporary table (12). The wafer (S) is transferred, the wafer (S) from the wafer chuck mechanism (41) is stored in the cassette (11b), and the wafer temporary placement table (12) is positioned in the wafer receiving zone (z1). Transfer to an empty (or empty) wafer chuck mechanism (41) is performed.

  Subsequently, the turntable (3) is rotated 90 degrees to move the wafer chuck mechanism (43) to the finish grinding zone (z4), and the wafer chuck mechanism (43) is stopped from the finish grinding zone (z4). . The wafer chuck mechanism (43) stopped in the zone (z4) is designated as (44) in accordance with the work performed there. As in the rough grinding zone (z3) in the zone (z4) and in the rough grinding zone (z3) in the finish grinding zone (z4), the liquid containing finely ground silicon particles before or simultaneously with the movement is used. The moving collection tray section (64a2) for collecting the wafer is advanced and inserted into the gap (K) below the chucking table (44a) of the wafer chuck mechanism section (44) in the zone (z4). In this state, the third spindle shaft (54a) is lowered to press the diamond grindstone (54c) against the back surface of the wafer (S), and the wafer chuck mechanism unit is supplied with pure water from the pure water supply nozzle (74). The chucking table (44a) and the third spindle shaft (53a) of (44) are rotated to remove the very small amount necessary for finish grinding of the back surface of the wafer (S) (the strain layer generated by rough grinding can be removed). Amount)). The finely ground silicon fine particles are also pure silicon that can be used as a silicon raw material. Also in this case, a very small amount of carbon constituting the diamond grindstone (54c) is contained as an impurity.

  The pure silicon fine particles that have been ground in the same way are fine particles with an average particle size of about 1 micron · meter and become slurry with a large amount of pure water supplied at the time of rough grinding as described above, and move with the table-side fixed collection tray (64a1). It flows into the base plate side fixed recovery tray part (64a3) via the recovery tray part (64a2), and is recovered through the drain pipe (64a33).

  When finish grinding is completed, the diamond grinding wheel (54c) for rough grinding is raised as described above, and pure water is supplied while rotating the chucking table (44a) of the wafer chuck mechanism (44) located in the same zone (z4). The supply is continued, and the chucking table (44a) and the wafer (S) sucked and fixed thereon are cleaned. When the cleaning is completed, the rotation of the chucking table (44a) and the supply of pure water are stopped, and then the finishing movement collection tray part (64a2) is retracted and detached from the chucking table (44a).

  When finish grinding is finished, the diamond grinding wheel (54c) for finish grinding is raised, and pure water is supplied while rotating the chucking table (44a) of the wafer chuck mechanism (44) located in the same zone (z4). Subsequently, the chucking table (44a) and the wafer (S) sucked and fixed thereon are cleaned. When the cleaning is completed, the rotation of the chucking table (44a) and the supply of pure water are stopped, and then the finish grinding silicon fine particle-containing liquid recovery tray (64) is retracted and detached from the chucking table (44a). Also here, unlike the backside impurity layer removal grinding, it is not necessary to clean completely, so it is possible to finish the cleaning simultaneously with the end of grinding.

  During the same period as before, rough grinding in the rough grinding zone (z2), impurity layer grinding removal in the impurity layer removal zone (z2), and accommodation of the wafer (S) in the cassette (11b) in the wafer receiving zone (z1) Supply and transfer of the wafer (S) from the wafer loading cassette (11a) to the temporary wafer table (12) is performed.

  After that, when the turntable (3) is rotated by 90 degrees and the wafer chuck mechanism (44) is moved to the wafer receiving zone (z1), the turntable (3) makes one turn, and the wafer chuck The wafer chuck mechanism section following the mechanism section (44) also moves to the respective zones (z2) to (z4) and stops, and the predetermined operation is performed in the zones (z2) to (z4).

  The wafer (S) attracted and fixed to the wafer chuck mechanism (44) moved to the wafer receiving zone (z1) around the circumference has been scraped to the specified thickness, and the wafer cleaning mechanism (13) is on the right side in the figure. The wafer (S) that has been ground with the cleaning side transfer vacuum tweezers (16a) is transferred to the wafer cleaning mechanism (13), cleaned as described above, and then moved by the articulated robot hand mechanism (8). It is stored in a storage cassette (11b).

  In addition, instead of the collection tray mechanism sections (62) to (64) shown in FIGS. 3 to 5, the collection tray mechanism section (62) composed only of the moving collection tray sections (62c) to (64c) as shown in FIG. ') To (64') may be used. In this case, notches (62a ') to (64a') formed to avoid the rotating shafts (42c) to (44c) so that they can be inserted / removed under the chucking tables (42a) to (44a) are formed to the tip. Has been. In this case, the outer walls (62e) to (64e) are so high that they can surround the chucking tables (42a) to (44a), while the inner walls (62f) to (64f) are chucked. It is formed low so as not to interfere with the tables (42a) to (44a).

  As described above, before the rough grinding, the impurity layer formed on the back surface of the wafer is pre-ground and removed by impurity layer removal back surface grinding, and only pure silicon fine powder obtained by rough and finish grinding is recovered. Therefore, the present invention can solve a serious short supply of raw material silicon.

Plan view of the back grinding apparatus of the present invention The perspective view of this invention back grinding machine The top view of the collection tray mechanism part of the device of the present invention Sectional view at the time of collection by the moving collection tray part of FIG. Sectional view when the moving recovery tray part of FIG. 3 is retracted Partial sectional view of the turntable portion of zones 1 and 3 of the device of the present invention Partial sectional view of the turntable portion of zones 2 and 4 of the device of the present invention The perspective view of the other movement collection tray part of the present invention The perspective view of the wafer cleaning mechanism part of this invention apparatus

Explanation of symbols

(A) Back grinding machine
(S) Wafer
(sf) Impurity layer
(z1) Wafer receiving zone
(z2) Backside impurity layer removal zone
(z3) Back rough grinding zone
(z4) Back surface finishing grinding zone
(1) Wafer supply mechanism
(2) Wafer back grinding unit
(3) Turntable
(41)-(44) Wafer chuck mechanism
(52) Backside impurity layer removal grinding mechanism
(53) Back rough grinding mechanism
(54) Back finish grinding mechanism
(72)-(74) Pure water supply nozzle

Claims (4)

(a) In the integrated circuit pattern forming process for forming an integrated circuit pattern on the front surface, at least the impurity layer is removed by grinding the back surface of the wafer on which the impurity layer is laminated on the back surface;
(b) Impurity layer removal After the backside grinding, the wafer is subjected to impurity removal cleaning,
(c) The back surface of the wafer after the impurity removal cleaning is ground while supplying pure water to obtain a wafer having a predetermined thickness, and the silicon fine particles generated by the grinding are recovered together with pure water.
(d) A method for grinding a back surface of a wafer, comprising finish grinding the back surface of the wafer. (a) A wafer supply mechanism that receives one wafer at a time after the semiconductor process is finished and an impurity layer is formed on the entire outer surface of the wafer, and a wafer back that grinds the back of the wafer supplied from the wafer supply mechanism A wafer backside grinding device composed of a grinding device part,
(b) The wafer back surface grinding device is divided into 4 categories: wafer receiving zone, back surface impurity layer removal zone, back surface rough grinding zone, and back surface finish grinding zone.
(b1) a turntable having at least four wafer chuck mechanism portions provided at equal intervals and rotating the wafer chuck mechanism portion intermittently in turn in each zone by rotation;
(b2) A back surface impurity layer removal grinding mechanism portion that is provided at a position facing the wafer chuck mechanism portion at the stop position of the turntable other than the wafer receiving zone, and performs predetermined grinding on the back surface of the wafer at each stop position, Back rough grinding mechanism and back finishing grinding mechanism;
(b3) When the turntable is stopped, a recovery tray mechanism section that is inserted below the wafer chuck mechanism section at the stop position of the turntable other than the wafer receiving zone and collects the silicon fine particle-containing liquid generated by the back surface grinding,
(b4) Pure water is supplied to the wafer chucked by the wafer chuck mechanism during grinding at the stop position of the turntable other than the wafer receiving zone, and at least at the back surface impurity layer removal grinding mechanism, It consists of a pure water supply nozzle that supplies water to clean and remove the silicon fine particle-containing liquid after grinding.
(c) A wafer back surface grinding device characterized by the above. In the wafer back surface grinding apparatus according to claim 2,
The moving recovery tray of the recovery tray mechanism for recovering the silicon fine particle-containing liquid surrounds the chucking table of each chuck mechanism that chucks the wafer for grinding. A wafer back surface grinding apparatus, wherein the wafer back surface grinding apparatus is controlled to be detached from each chuck mechanism when the turntable is moved. In the wafer back surface grinding apparatus according to claim 2,
The collection tray set of the collection tray mechanism for collecting the silicon fine particle-containing liquid is
(1) A table-side fixed collection tray portion fixed below each chucking table so as to surround the chucking table of each chuck mechanism portion;
(2) A movable collection tray section that is inserted between the table-side fixed collection tray section and each chucking table when the turntable is stopped and controlled so as to be detached from each chucking table when the turntable is moved;
(3) A base plate side fixed collection tray unit that is fixed to the base plate side of the wafer back surface grinding mechanism unit and collects the silicon fine particle-containing liquid ground from at least one of the table side fixed collection tray unit and the moving collection tray unit. A backside grinding apparatus for a wafer, comprising:

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