Method for cutting substrate and sheet for fixing semiconductor at cutting

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a method for cutting a semiconductor substrate and a sheet for fixing a semiconductor substrate at the time of cutting, and is useful, for example, when a silicon wafer is diced to a chip using a diamond blade or the like.

【0002】

[Conventional technology]

Conventionally, in order to dic a silicon wafer to a large number of chips, the silicon wafer is attached to the adhesive surface of a single-sided adhesive sheet provided with an adhesive layer whose adhesive strength is reduced by irradiation or heating of ultraviolet rays on one side. Is placed on a suction-type dicing table on the non-adhesive side of the single-sided adhesive sheet, and the silicon wafer is suction-fixed by vacuuming in the dicing table while dicing with a diamond blade or the like. After that, evacuation is stopped, cutting chips are removed by washing, the adhesive sheet is peeled off by ultraviolet irradiation or heating, and the sheet is transferred to the next step.

【0003】

However, in this dicing method, cutting chips tend to adhere to the chip and the blade due to the adhesive content, which leads to deterioration of the quality of the chip and early wear of the blade, and also an expensive ultraviolet irradiation device and temperature. A control device is required and the equipment cost is high. Further, it is necessary to make the dicing table a considerably fine porous material, clogging is likely to occur due to cutting chips, and there is a concern that the position of the silicon wafer may be displaced due to a decrease in suction force.

【0004】

[Problems to be Solved by the Invention]

The applicant mainly placed a porous sheet made of ultra-high molecular weight polyethylene on a base having ventilation holes as a fixing method in the processing process of a glass plate for liquid crystal, a polarizing plate, and a retardation plate. Then, the workpiece is placed on the porous sheet, and the workpiece is fixed on the porous sheet by reducing the pressure through the ventilation holes. " Has already been proposed (Japanese Patent Laid-Open No. 8-169971, Japanese Patent Laid-Open No. 9-22935). According to this adsorption fixing method, the semiconductor substrate can be fixed without using an adhesive sheet, and it can be expected that defects caused by the adhesive in the silicon wafer dicing can be eliminated.

【0005】

Therefore, the present inventors have attempted to fix and dice the silicon wafer by the above suction fixing method. However, if the porous sheet is cut by the cutting edge that appears on the back surface of the silicon wafer, the adsorption interface between the porous sheet and the dicing table becomes unstable, and the wafer shifts inevitably. There was found. That is, in the state until the cutting edge appears on the back surface of the wafer, as shown in (a) of FIG. 5, the load W acting on the wafer 2'by the rotational cutting force of the blade 3'is the rigidity of the wafer 2'. As a result of being dispersed over the entire surface of the porous sheet A', it acts on the interface between the porous sheet A'and the wafer 2'and the interface between the porous sheet A'and the dicing table 1'. The load stress w to be applied becomes evenly distributed, and these interfaces are stably maintained. However, as shown in Fig. 5 (b), when the porous sheet A'is cut by the blade 3', the porous sheet A'is cut. As a result of the load W acting intensively on the local p'at the interface between the porous sheet A'and the dicing table 1', the local part is peeled off without being able to withstand the load. The destabilization of the interface progresses.

【0006】

An object of the present invention is to place a semiconductor substrate on a suction type table via a porous sheet, and suck the semiconductor substrate through the continuous pores of the porous sheet by vacuum suction of the suction type table. The purpose is to enable good dicing with a blade while fixing.

【0007】

[Means for solving problems]

In the method for cutting a semiconductor substrate according to the present invention, the semiconductor substrate is placed on a suction type table via a porous sheet, and the suction type table is sucked under reduced pressure to continuously pore the porous sheet. It is a method of cutting a semiconductor substrate with a blade while sucking and fixing the semiconductor substrate through the semiconductor substrate, and is characterized in that a groove is formed in a portion of the surface of a porous sheet in contact with the semiconductor substrate that faces directly below the cut portion of the substrate. It is a composition.

【0008】

The sheet for fixing at the time of cutting a semiconductor substrate according to the present invention is a porous sheet used in the method for cutting a semiconductor substrate, and is directly below the cut portion of the substrate on the surface of the porous sheet in contact with the semiconductor substrate. The structure is characterized by forming a groove in the portion facing the groove, an airtight film is provided on the inner surface of the groove, and a sintered body of ultra-high molecular weight polyethylene powder is used for the porous sheet. be able to.

【0009】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings. (A) of FIG. 1 shows an example of an apparatus used in the method for cutting a semiconductor substrate according to the present invention. In (a) of FIG. 1, 1 is a suction type dicing table, and a vacuum drawing box 13 is attached to the back surface of a base plate 12 having a suction groove 11 on the front surface, and the inside of the box 13 and the suction groove 11 are passed through. It communicates with pores 14. A is a porous sheet with continuous pores placed on the dicing table 1, 2 is a silicon wafer placed on the porous sheet A, and 3 is a blade.

【0010】

In order to dic the silicon wafer 2 according to the present invention, in order to provide a groove on the surface of the porous sheet A so as to face directly under the cutting portion of the silicon wafer, the porous sheet shown in FIG. ), Fig. 2 (b) [Ro-ro cross section in Fig. 2 (a)] and Fig. 2 (c) [Ha-ha cross section in Fig. 2 (a)], dicing pattern Using the fixing sheet according to the present invention in which the groove a of the same pattern as the wafer is formed on the surface, the inside of the vacuuming box 13 of the dicing table 1 is vacuumed to make the wafer 2 a porous sheet. Dicing with a predetermined pattern by blade 3 while sucking and fixing through the continuous pores of the wafer A, and letting the cutting edge 31 escape to the groove a of the porous wafer A as shown in (b) of FIG. The silicon wafer 2 is cut without cutting the porous sheet A. In order to prevent vacuum leakage through the groove a, the end of the groove is filled with a seal material c, for example, a resin such as fluororubber, epoxy resin, or polyethylene, as shown in FIG. 2 (b). , Or, as shown in FIG. 3, it is terminated leaving the partition wall portion e.

【0011】

In the above dicing, as long as the porous sheet A is not cut by the cutting edge of the blade 3, that is, there is no contact between the porous sheet A and the blade 3, the rotary cutting of the blade 3 is performed. The force is transmitted to the interface between the wafer 2 and the porous sheet A and the interface between the porous sheet A and the dicing table 1 via the silicon wafer 2, and is shown in FIG. 5 (b). When the quality sheet is cut by the cutting edge, it is possible to avoid the situation where the load is concentrated on the local p'at the interface between the porous sheet and the dicing table, so the wafer is stably fixed during dicing. This can guarantee high-precision and stable dicing of silicon wafers.

【0012】

During or after the above dicing, a cleaning liquid is sprayed to remove cutting chips on the silicon wafer. Since the cutting chips do not contain an adhesive and have grooves on the surface of the porous sheet, the cutting chips can be efficiently cleaned and removed.

【0013】

In the above, in order to prevent the degree of decompression from decreasing due to the suction of air from the groove surface of the porous sheet even if the silicon wafer is incised and air flows into the groove through the incision, the figure is shown in the figure. As shown in 2 and FIG. 3, it is desirable to form an airtight film f, for example, a coating film of a resin solution such as an epoxy resin solution on the inner surface of the groove a. Further, as shown in FIGS. 2 and 3, it is preferable to provide the airtight film g on the end surface of the porous sheet A as well.

【0014】

The groove formation on the surface of the porous sheet can be performed by cutting or heating embossing. In the latter case of heat embossing, an airtight film is formed on the inner surface of the groove by melting and solidifying the sheet material, so that the above resin liquid does not need to be applied. If the pore size and porosity of the porous sheet are too small, a high suction pressure is required, and if it is too large, the exhaust flow rate becomes large and decompression becomes difficult. Therefore, the pore diameter is 1 μm to 400 μm and the porosity is 5%. It is preferably ~ 60%, but is not limited to this range.

【0015】

The higher the rigidity of the porous sheet, the wider the suction groove width of the dicing table can be, and the more the porous sheet can be prevented from falling into the groove. Increasing the thickness and widening the suction groove width of the dicing table is advantageous for preventing clogging of the dicing table.

【0016】

The dimensions of the porous sheet are set in consideration of the protrusion height of the blade cutting edge from the back surface of the wafer, the suction groove width of the dicing table, etc., but in the case of dicing of a silicon wafer, for example, the outer diameter. 200 mmφ, thickness 1 mm, groove depth 0.5 mm, groove width 1 mm, groove pitch 6 mm. The shape of the groove can be the square groove shown in (c) of FIG. 2 or the triangular groove shown in FIG.

【0017】

The material of the porous sheet for fixing when cutting a semiconductor substrate according to the present invention is ultra-high molecular weight polyethylene (viscosity average molecular weight is 500,000 to 500,000 or more) in terms of prevention of scratches and toughness suitable for cutting. It is preferable to use a sintered porous body of 10 million, preferably 1 million to 7 million) powder. This ultra-high molecular weight polyethylene powder sintered porous sheet is prepared by filling a mold with ultra-high molecular weight polyethylene powder, pressurizing the powder at a predetermined pressure, and then in a heating furnace above the melting point of the ultra high molecular weight polyethylene. It can be manufactured by sintering, cooling and demolding to obtain a round bar-shaped molded body, peeling and cutting it into a sheet having a predetermined thickness with a lathe or the like, and punching this sheet into a predetermined shape. The pore size and porosity can be controlled by the particle size of the powder, and it is preferable to use an ultra-high molecular weight polyethylene powder having an average particle size of 30 to 170 μm, preferably 100 to 170 μm. (Made by Chemical Industry Co., Ltd.) and Hostalem Blade UR (manufactured by Tycona Co., Ltd.) can be mentioned.

【0018】

In the production of the above-mentioned ultra-high molecular weight polyethylene powder sintered porous sheet, "the ultra high molecular weight polyethylene powder is filled in a mold, the powder is heated at a temperature lower than its melting point, and then at a predetermined pressure. A preformed product is pressurized to obtain a preformed product, and the preformed product is exposed to a reduced pressure atmosphere to remove air in the preformed product, and then sintered and cooled in a heated steam atmosphere equal to or higher than the melting point of ultrahigh molecular weight polyethylene. It is also possible to use a method of demolding to obtain a round bar-shaped molded body, peeling and cutting it into a sheet having a predetermined thickness, and punching this sheet into a predetermined shape (Patent No. 2020026).

【0019】

[Effect of the invention]

According to the present invention, a semiconductor substrate is placed on a suction type table via a porous sheet, and the semiconductor substrate is sucked through the continuous pores of the porous sheet by vacuum suction of the suction type table. When dicing with a blade while fixing, a groove is formed on the surface of the porous sheet to prevent the porous sheet from being cut by the cutting edge that appears on the back surface of the substrate. -A high-rigidity semiconductor that can eliminate the rotational cutting force load of the cutting edge from acting intensively on the interface between the porous sheet and the suction dicing table due to the cutting into the porous sheet of the cutting edge. The load can be applied to the entire interface via the substrate, the interface can be stably held, the semiconductor substrate can be fixed without shifting, and dicing can be performed with high accuracy. Furthermore, since the cutting chips of the semiconductor substrate do not contain an adhesive and the grooves on the surface of the porous sheet enhance the cleaning effect, high-efficiency cleaning can be guaranteed, and chip damage and blade wear are good. This can be prevented, and high quality chips and long blade life can be achieved.

[Simple explanation of drawings]

[Figure 1]

It is a drawing which shows the cutting method of the semiconductor substrate which concerns on this invention.

[Figure 2]

It is a drawing which shows the sheet for fixing at the time of cutting the semiconductor substrate which concerns on this invention.

[Fig. 3]

It is a drawing which shows the main part of another example of the sheet for fixing at the time of cutting a semiconductor substrate which concerns on this invention.

[Fig. 4]

It is a drawing which shows the main part of the example different from the above of the sheet for fixing at the time of cutting a semiconductor substrate which concerns on this invention.

[Fig. 5]

It is a drawing which shows the cutting method of the semiconductor substrate which used the ordinary porous sheet as the fixing sheet at the time of cutting a semiconductor substrate.

[Explanation of symbols]

A Porous sheet a groove 1 Dying table 13 Evacuation box 2 Semiconductor substrate 3 blade