CN1299336C - Wafer Back Grinding Process - Google Patents

Abstract

A wafer backside grinding process. The invention provides a semiconductor process for integrating processes, reducing carrying actions, preventing wafer warping and cracking and positioning really, which comprises a wafer providing step of providing a wafer with a main surface and a back surface, a wafer loading step of loading the wafer on a grinding disc in an adsorption and fixing mode and exposing the back surface of the wafer, a wafer grinding step of grinding the back surface of a wafer on the grinding disc, a positioning piece attaching step of attaching a positioning piece to the ground back surface of the wafer and a wafer unloading step of detaching the wafer from the grinding disc by removing the adsorption force of the grinding disc; the step of grinding the wafer and the step of attaching the positioning piece are all to load the wafer on a grinding disc, and the grinding disc keeps the adsorption force to the wafer in the step of attaching the positioning piece; in the step of unloading the wafer, the positioning element is used as a carrier to move the wafer.

Description

Wafer Back Grinding Process

technical field

The invention belongs to semiconductor technology, in particular to a wafer back grinding technology.

Background technique

With the thinning trend of semiconductor package components, the chips in the package components also need to comply with thinner thickness. Therefore, a wafer backside grinding process is proposed. The conventional wafer back grinding process is implemented after the integrated circuit manufacturing process and before the wafer dicing process, so that multiple chips on the wafer can be thinned at one time.

As shown in Figure 1 and Figure 2, the traditional wafer back grinding process and wafer cutting process include the following steps:

step one

Provide wafer

A wafer 20 having an active surface 21 for forming an integrated circuit and a corresponding back surface 22 is provided, and a protective tape 23 is usually pasted on the active surface 21 of the wafer 20 .

step two

Load wafer

Vacuum adsorption is adopted, and the wafer 20 is adsorbed and fixed on the grinding chuck 31 with the wafer active surface 21 facing the grinding chuck 31, so that the wafer 20 is loaded on the traditional wafer backside grinding equipment. , the backside 22 of the wafer 20 is exposed.

step three

Grinding wafer

The backside 22 of the wafer 20 is ground by the grinding head 32 to form a thinner ground backside 221 .

step four

unload wafer

The polished backside 221 of the wafer 20 is contacted by the suction device, and the wafer 20 is taken out from the grinding equipment.

step five

remove tape

The taken-out wafer 20 is transferred to a tape removal stage to remove the protective tape 23 .

step six

Positioning before dicing wafers

Paste another positioning tape on the back side 221 of the wafer 20 .

step seven

Dicing wafer

The wafer 20 is moved to the wafer dicing equipment, and the wafer 20 is diced.

As mentioned above, between step 4 of unloading the wafer and step 7 of dicing the wafer, multiple moving actions are required for machine conversion. Due to the known small size, such as 4in or 6in wafers, the wafer warpage (wafer war page) after back grinding is still not obvious, especially in an acceptable range, but as the wafer size increases, such as 6in Above, or the thickness of the grinding is more stringent, such as below 12 mils, as shown in Figure 2, the warping of the wafer 20 after grinding is quite obvious, and the occurrence of this warping is more due to the residual stress of the wafer integrated circuit process. And the thinning of the semiconductor base layer such as silicon becomes so serious that the chipping of the wafer 20 is very likely to be caused in the fourth step of unloading the wafer or in the subsequent handling steps.

The disclosed wafer dicing process is to pre-cut the wafer before grinding. The back of the wafer is pasted with the first tape. After the wafer is cut, the second tape is pasted on the active surface and the first tape is removed. After grinding, the wafer is formed into multiple wafers, and then the third tape is pasted on the back of multiple wafers after thinning and the second tape is removed. Therefore, the number of flipping and handling is quite frequent, and the alignment of wafers requires strict requirements. , In addition, when excessive grinding is required, the wafers that have been separated in the second tape may have displacement deviation or collision damage during grinding due to insufficient adhesion.

Contents of the invention

The object of the present invention is to provide a wafer back grinding process which integrates the process, reduces the handling action, prevents the warping and cracking of the wafer, and ensures accurate positioning.

The present invention includes the step of providing a wafer with an active surface and a wafer on the back side, loading the wafer on the grinding disc in a suction-fixed manner and exposing the back side of the wafer, and carrying out the wafer backside on the grinding disc. The step of grinding the wafer for grinding, the step of attaching the positioner for attaching the positioner on the backside of the wafer after grinding, and the step of unloading the wafer from the grinding disc by removing the adsorption force of the grinding disc; the step of grinding the wafer and In the step of attaching the positioning member, the wafer is loaded on the grinding disc, and the grinding disc maintains the adsorption force on the wafer during the attaching step of the positioning member; in the step of unloading the wafer, the positioning member is used as a carrier to move wafer.

in:

In the step of providing the wafer, an adhesive protective tape is pasted on the active surface of the wafer.

The size of the wafer in the wafer providing step can be 8in or 12in.

The wafer grinding step is divided into rough grinding and fine grinding.

In the step of grinding the wafer, the thickness of the wafer is ground to less than 12 mils.

The positioning piece in the positioning piece attachment step includes a positioning ring and a positioning tape. The positioning ring has an opening larger than the size of the wafer; the positioning tape is attached to the positioning ring and attached to the backside of the wafer after grinding through the opening.

The step of attaching the positioning member is to first place the positioning ring of the positioning member on the grinding disc, and then attach the positioning tape to the positioning ring and the backside of the wafer after grinding by rolling.

A wafer backside grinding process, which includes a step of loading a wafer on a grinding disc in a suction-fixed manner and exposing the back side of the wafer, a grinding step of grinding the back side of the wafer on the grinding disc, and The positioner attaching step of attaching the positioner on the backside of the wafer after grinding; in the step of grinding the wafer and the step of attaching the positioner, the wafer is loaded on the grinding disc, and ground in the step of attaching the positioner The disk maintains the suction force to the wafer so that the positioning part is flatly attached to the backside of the wafer after grinding.

In the attaching step of the positioning member, the positioning member includes a positioning ring and a positioning tape. The positioning ring has an opening larger than the size of the wafer; the positioning tape is attached to the positioning ring and attached to the back of the wafer after grinding through the opening, so that the subsequent handling process There is no need to contact the backside of the wafer after grinding.

In the attaching step of the positioning member, the positioning member is a positioning member suitable for a wafer cutting process.

Because the present invention includes the step of providing the wafer with the active surface and the back wafer, loading the wafer on the grinding disc in a suction-fixed manner and exposing the wafer backside step, and aligning the wafer backside on the grinding disc. The step of grinding the wafer for grinding, the step of attaching the positioning member to the backside of the wafer after grinding, and the step of unloading the wafer from the grinding disc by removing the adsorption force of the grinding disc; the step of grinding the wafer In the step of attaching the positioning member, the wafer is loaded on the grinding disc, and the grinding disc maintains the adsorption force on the wafer in the step of attaching the positioning member; in the step of unloading the wafer, the positioning member is used as a carrier Move the wafer. In the wafer back grinding equipment, the wafer is adsorbed on the grinding disc, and the same grinding disc is used to carry out the steps of loading the wafer, grinding the wafer, attaching the positioning part, unloading the wafer, etc. After grinding, the wafer is attached Attached to the positioning tape attached to the positioning piece, the positioning piece can be used as a carrier for the wafer during the wafer unloading step and subsequent steps of handling without touching the backside of the wafer after grinding, so it has process integration, It has the effect of reducing the movement and preventing the wafer from warping and cracking after grinding, especially suitable for ultra-thin grinding of large-sized wafers. Not only the process is integrated and the handling action is reduced, but also the warping and fragmentation of the wafer is prevented and the positioning is accurate, so as to achieve the purpose of the present invention.

Description of drawings

Figure 1 is a block diagram of the traditional wafer back grinding and dicing process.

Figure 2 is a schematic diagram of a traditional wafer back grinding process.

Fig. 3 is a flow block diagram of the present invention.

Fig. 4 is a schematic diagram of Step 1 of the present invention.

Fig. 5 is a schematic diagram of Step 2 of the present invention.

Fig. 6 is a schematic diagram of Step 3 of the present invention.

Fig. 7 is a schematic diagram of Step 4 of the present invention.

Fig. 8 is a schematic diagram of Step 5 of the present invention.

Fig. 9 is a schematic diagram of Step 6 of the present invention.

Fig. 10 is a schematic diagram of Step 7 of the present invention.

Fig. 11 is a schematic flow chart of the present invention.

Fig. 12 is a schematic diagram of the equipment used in the present invention.

Detailed ways

As shown in Fig. 3, Fig. 11, Fig. 12, the present invention comprises the following steps:

step one

Provide wafer

As shown in FIG. 4 , a wafer 50 having an active surface 51 and a corresponding back surface 52 is prepared, and an integrated circuit has been fabricated on the active surface 51 , such as a microprocessor, a microcontroller, a memory or an integrated circuit for special applications. Preferably, the wafer 50 is a high frequency memory, such as random access memory such as DDR, Rambus, TDR or QDR. The size of the wafer can be 4in, 5in, 6in, 8in or 12in, preferably, the wafer is 8in or 12in; preferably, a peelable adhesive protective tape 53 is attached to the active surface 51 of the wafer 50 .

step two

Load wafer

As shown in FIG. 5 , the wafer 50 is loaded (loading) on the grinding chuck (grinding chuck) 61 of the wafer back grinding device 90 by means of adsorption and fixation such as vacuum adsorption or electrostatic adsorption, and the back surface 52 of the wafer 50 is exposed. .

step three

Grinding wafer

As shown in Figures 11 and 12, the grinding disc 61 uses the movement of the loading arm 911 at the loading station 91 of the wafer back grinding device 90 to load the wafer 50 onto the grinding disc 61, and then the grinding disc 61 is moved along the The axis rotates to the grinding workstation 92 to grind the wafer 50 .

The grinding wafer area is divided into the rough grinding operation performed at the rough grinding workstation 92 and the fine grinding operation performed at the fine grinding workstation 93; as shown in FIG. ,, as shown in FIG. 6, the back surface 52 of the wafer 50 is ground with an appropriate grinding head 62 to form a ground back surface 521. According to different thickness requirements, the thickness of the ground wafer 50 can reach below 12 mils (mil). Since the process of the present invention does not need to consider the warpage of the wafer 50, the thickness of the wafer 50 after grinding can even reach 6 mils, 4 mils or even lower.

step four

Positioner attachment

Grinding disk 61 rotates to positioner attaching workstation 94; preferably first cleans wafer 50 with deionized water, which can be provided with a wafer cleaning device at positioner attaching workstation 94 and executed at positioner attaching workstation 94 ; Can also be processed by additional workstations.

As shown in FIG. 11 and FIG. 12 , the grinding disc 61 rotates to the positioning member attaching workstation 94 . As shown in FIG. 7 , the positioning member 70 is attached to the back surface 521 of the wafer 50 after grinding on the grinding disc 61. During the attachment process, the grinding disc 61 still maintains the adsorption force to the wafer 50, so that the wafer 50 is horizontal. It is arranged on the grinding disc 61 so that the positioning member 70 is flatly attached to the back surface 521 of the wafer 50 after grinding. The positioning member 70 includes a positioning ring 71 and a positioning tape 73. The positioning ring 71 has an opening 72 larger than the size of the wafer 50. Generally speaking, the positioning ring 71 is a hard metal ring; the positioning tape 73 is attached to the positioning ring 71 and passed through The opening 72 is attached to the back surface 521 of the wafer 50 after grinding; preferably, the positioning member 70 is suitable for a wafer cutting process. As shown in FIG. 7 and FIG. 12 , the positioning member attaching workstation 94 is provided with a rolling device 63 , which can be a roller coated with soft rubber. When attaching the positioning member, after the grinding disc 61 is positioned, the positioning ring 71 of the positioning member 70 is first set on the grinding disc 61, and then the large-area positioning tape 73 is rolled by the rolling device 63 in a rolling manner On the positioning ring 71 and the back side of the wafer 50, the positioning tape 73 is attached to the positioning ring 71 and the back side of the wafer 50 at the same time, and then the positioning tape 73 is appropriately cut to form a positioning piece 70 that is pasted on the back side 521 of the wafer 50 after grinding .

step five

unload wafer

As shown in Figure 8, Figure 11 and Figure 12, the grinding disc 61 rotates to the unloading workstation 95; preferably the unloading workstation 95 and the loading workstation 91 are integrated into the same workstation, that is, the adsorption force of the grinding disc 61 is first released, The wafer 50 that has been ground can be separated from the grinding disc 61. The wafer 50 is usually slightly warped when there is no suction force, and the wafer 50 is moved by the positioning member 70, that is, the unloading arm 912 or other The device fixes the positioning ring 71 so that the wafer 50 can be unloaded from the wafer back grinding equipment 90 without touching the ground backside 521 of the wafer 50 for subsequent steps.

step six

remove tape

As shown in FIG. 9 , the taken-out wafer 50 is moved to the tape removal stage 81 by using the positioning member 70 as a carrier of the wafer 50 to remove the protective tape 53 .

step seven

Dicing wafer

As shown in FIG. 10 , the wafer 50 is transported to the wafer cutting equipment with the positioning member 70 as the carrier of the wafer 50, and the positioning tape 73 of the positioning member 70 is attached to the cutting table 82 of the wafer cutting equipment to cut Tool 83 cuts wafer 50 into wafers 54 .

Therefore, according to the present invention, in the wafer back grinding equipment, the wafer 50 is adsorbed on the grinding disc 61, and the same grinding disc 61 is used to carry out the steps of loading the wafer, grinding the wafer, attaching the positioning member, and unloading the wafer. , after grinding, the wafer 50 is attached to the positioning adhesive tape 73 of the positioning member 70, and the positioning member 70 can be used as a carrier for the wafer 50 during the removal of the wafer step and the subsequent steps of moving. There is no need to contact the ground backside 521 of the wafer 50. The positioning piece 70 is suitable for wafer backside grinding equipment and wafer cutting equipment. The positioning tape 73 of the positioning piece 70 is attached to the cutting table 82 of the wafer cutting equipment to cut The tool 83 cuts the wafer 50 into a plurality of wafers 54. Therefore, the present invention has the functions of process integration, reduction of handling operations and prevention of chipping of the wafer after grinding, and is especially suitable for ultra-thin grinding of large-sized wafers.

Claims (10)

1, a kind of wafer reverse side grinding technology, it comprise provide have active surface and back side wafer the wafer step is provided, with the absorption fixed form with wafer load on the abrasive disk and make the loading wafer step that wafer rear manifests, the grinding wafer step of on abrasive disk, chip back surface being ground and unload the wafer step by what remove that the abrasive disk absorption affinity makes that wafer breaks away from abrasive disk; It is characterized in that described grinding wafer step and unload the keeper attaching step that the back side that is provided with between the wafer step behind grinding wafer attaches keeper; Grind in the step that wafer step and keeper attach all be with wafer load on abrasive disk, and attach in the step abrasive disk maintenance to the absorption affinity of wafer at keeper; Unloading in the wafer step is to move wafer with keeper as carrier.

2, wafer reverse side grinding technology according to claim 1 is characterized in that describedly providing that the active surface in wafer is pasted with the stickiness protective tapes in the wafer step.

3, wafer reverse side grinding technology according to claim 1 is characterized in that the described size of wafer in the wafer step that provides can be 8in or 12in.

4, wafer reverse side grinding technology according to claim 1 is characterized in that described grinding wafer step divides into rough lapping and fine lapping.

5,, it is characterized in that the thickness of wafer in the described grinding wafer step is to be ground to below 12 Mills according to claim 1 or 4 described wafer reverse side grinding technologies.

6, wafer reverse side grinding technology according to claim 1 is characterized in that the keeper of described keeper attaching step comprises locating ring and locating adhesive tape, and locating ring has the opening greater than wafer size; Locating adhesive tape is to be attached at locating ring and to be attached at the back side behind the grinding wafer via opening.

7, wafer reverse side grinding technology according to claim 6, it is characterized in that it is earlier the locating ring of keeper to be arranged on the abrasive disk that described keeper attaches step, in the roll extrusion mode locating adhesive tape is attached at the back side behind locating ring and the grinding wafer simultaneously again.

8, a kind of wafer reverse side grinding technology, it comprises with the absorption fixed form wafer load on the abrasive disk and make loading wafer step that wafer rear manifests and the grinding wafer step of on abrasive disk chip back surface being ground; It is characterized in that being provided with after the described grinding wafer step keeper that the back side behind grinding wafer attaches keeper and attach step; Grind in the step that wafer step and keeper attach all be with wafer load on abrasive disk, and keeper attach abrasive disk maintenance in the step to the absorption affinity of wafer so that keeper is smooth be attached at grinding wafer after the back side.

9, wafer reverse side grinding technology according to claim 8 is characterized in that keeper comprises locating ring and locating adhesive tape in the described keeper attaching step, and locating ring has the opening greater than wafer size; Locating adhesive tape is to be attached at locating ring and to be attached at the back side behind the grinding wafer via opening, so that do not need to contact the back side behind the grinding wafer in the follow-up handling process.

10, wafer reverse side grinding technology according to claim 8 is characterized in that keeper is the keeper that is applicable to the wafer cutting technique in the described keeper attaching step.

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