Grinding Configuration for Substrate Grinding Apparatus

Not applicable.

The present invention relates to a substrate grinding apparatus; in particular, it relates to a grinding configuration for a substrate grinding apparatus.

The substrate grinding apparatus primarily operates by driving an abrasive cloth to rotate through a grinding disk, using the abrasive cloth to grind the upper surface of a substrate placed thereunder; wherein the substrate may be a wafer, but is not limited to wafers.

A thickness measuring device is installed in the substrate grinding apparatus. While the grinding disk drives the abrasive cloth to grind the substrate, the thickness measuring device simultaneously measures the thickness of the substrate.

The substrate thickness measuring device is positioned above the grinding disk and includes an illuminator, a light receiver, and a computing unit. Multiple light channels are penetrated through the grinding disk, with each light channel extending through the abrasive cloth. The illuminator projects laser light through the light channel to irradiate the substrate being ground, the light receiver receives the reflected light of the laser light from the substrate, and the computing unit calculates the thickness of the substrate based on the reflected light.

The portion of the substrate removed by the abrasive cloth forms a powder. This powder mixes with the coolant used during grinding to form a slurry-like substance. This substance easily enters and accumulates in the light channels, obstructing the passage of the laser light or its reflected light. In addition, the coolant also easily generates a foam due to the relative rotation between the abrasive cloth and the substrate, and this foam can enter the light channels, causing refraction of the laser light or its reflected light, which affects the thickness accuracy obtained by the computing unit.

The main purpose of the present invention is to provide a grinding configuration for a substrate grinding apparatus. In order to achieve the above purpose, the present invention adopts the following technical solution:

A grinding configuration for a substrate grinding apparatus comprises a grinding disk used to install an abrasive cloth for grinding a substrate positioned beneath the abrasive cloth. Multiple mounting holes are penetrated through the grinding disk along an axial direction to define a virtual circular line, with a center of the circular line being located at a rotation center of the grinding disk, wherein each mounting hole is spaced along the circular line. Multiple first light guides and multiple second light guides are respectively provided in each mounting hole, wherein each of the first light guides and each of the second light guides is penetrated along its axial direction to form a light channel. Multiple light transmission plates through which light passes are provided at the lower end of each of the first light guides and each of the second light guides, wherein each light transmission plate blocks communication between each light channel and the space below the grinding disk, thereby preventing slurry or foam generated during grinding of the substrate from entering each light channel.

The present invention is capable of blocking the entry of the slurry-like substance or the foam into each light channel, reducing the impact of the slurry-like substance or the foam on the laser light or its reflected light passing through each light channel, and enhancing the thickness accuracy obtained by the thickness measuring device during operation.

Please refer to the drawings for a preferred embodiment of a grinding configuration of a substrate grinding apparatus of the present invention, but these embodiments are for illustrative purposes only and are not subject to the limitations of this structure for patent application.

As shown in, in the preferred embodiment of the present invention, a thickness measuring devicecan be combined. During the grinding of a substrate (not shown) in the preferred embodiment, the operation of the preferred embodiment does not need to be stopped, and the thickness measuring devicecan simultaneously measure the thickness of the substrate; wherein the substrate can be a wafer, but is not limited to wafers.

The preferred embodiment of the present invention includes a grinding disk, multiple first light guides, and multiple second light guides. The grinding diskis used to install an abrasive cloth, such that the abrasive clothcan be driven by the grinding diskto rotate, thereby grinding the substrate positioned beneath the abrasive cloth.

Multiple mounting holesare penetrated through the grinding diskalong an axial direction to define a virtual circular line, with a center of the circular linebeing located at a rotation centerof the grinding disk. The diameter direction of the circular lineis the same as the diameter direction of the grinding disk, and each mounting holeis spaced along the circular line.

Each of the first light guidesand each of the second light guidesis provided in each mounting hole, respectively. Each of the first light guidesand each of the second light guidesis penetrated along its axial direction to form a light channel. Multiple light transmission platesthrough which light can pass are provided at the lower end of each of the first light guidesand each of the second light guides, with each light transmission plateblocking the communication between each light channeland the space below the grinding disk, thereby preventing slurry or foam generated during grinding of the substrate from entering each light channel.

The thickness measuring deviceis positioned above the grinding diskand opposite any of the light channels. As the grinding diskrotates to drive the abrasive clothto grind the upper surface of the substrate, each light channelpasses sequentially below the thickness measuring device, and the thickness measuring devicesequentially projects laser light onto the substrate through each light channeland receives the reflected light of the laser light from the substrate through each light channel, so as to calculate the thickness of the substrate based on the reflected light.

The thickness measuring deviceis a prior art known to those skilled in the art of the present invention, and the thickness measuring deviceis not necessarily related to the technical features of the present invention, so the specific structure of the thickness measuring devicewill not be described in detail.

In order to allow the laser light and the reflected light to pass through the abrasive clothwithout obstruction or interference, the abrasive clothis provided with multiple through-holes. The formation of each through-holeis known to those skilled in the art of the present invention, and each through-holeis located at the axial extension of each mounting hole, wherein the diameter of each through-holeis larger than the diameter of each mounting hole.

The lower ends of each of the first light guidesand each of the second light guidesare each located near the lower surface of the grinding diskto avoid contact with the substrate during grinding by the abrasive cloth. Therefore, during grinding of the substrate by the abrasive cloth, the lower ends of each first light guideand each second light guideare preferably located above the lower surface of the abrasive cloth.

During grinding of the substrate by the abrasive cloth, each of the first light guidesand each of the second light guidesrotates around the rotation centerfollowing the circular linewithout the need to stop the operation of the grinding disk. The thickness measuring devicecan sequentially project laser light onto the substrate through each light channeland sequentially receive the reflected light of the laser light from the substrate through each light channel, whereby the thickness measuring devicecalculates and obtains the thickness of the substrate based on the reflected light.

The portion of the substrate removed by the abrasive clothforms a powder. The powder is mixed with the coolant used during grinding to form a slurry-like substance. The slurry-like substance cannot enter and accumulate in each light channeldue to the presence of each light transmission plate, and a foam generated by the relative rotation of the abrasive clothand the substrate also cannot enter each light channeldue to the blocking of each light transmission plate. Compared to the prior art, the preferred embodiment can reduce the impact of the slurry-like substance or foam on the laser light or the reflected light and increase the accuracy of the thickness of the substrate obtained by the thickness measuring device.

Multiple first positioning structuresare respectively connected to each of the first light guidesand for positioning each of the first light guides. Multiple second positioning structuresare respectively connected to each of the second light guidesand for positioning each of the second light guides.

The present invention may choose to respectively configure the first positioning structuresfor each of the first light guidesand not to respectively configure the second positioning structuresfor each of the second light guides; or the present invention may choose to respectively configure the second positioning structuresfor each of the second light guidesand not to respectively configure the first positioning structuresfor each of the first light guides, thereby forming multiple different alternative embodiments.

Each of the first positioning structuresincludes two clamping blocks, each of which cooperatively clamps the radial outer periphery of the first light guideand abuts the upper surface of the grinding disk, thereby axially positioning each of the first light guides.

Each of the first positioning structuresfurther includes a first fastening boltand a second positioning bolt. Each first fastening boltlocks each clamping blockagainst each other so that each clamping blockcan abut tightly against the outer periphery of each first light guide, thereby increasing the stability of each clamping blockin radially clamping each first light guide. Each second positioning boltis pivotally threaded through each clamping blockand screwed into the grinding diskto lock each clamping blockto the grinding disk, thereby increasing the stability of each first positioning structurein positioning on the grinding disk.

Each of the second positioning structuresincludes a bushingand a base, respectively. Each bushingtightly encloses the radial outer periphery of each second light guideand protrudes downward with two protrusions, which are spaced along the circumferential direction of the bushing. Each baseabuts against the upper surface of the grinding diskand protrudes upward with two riser blocksspaced along the circumferential direction of the base.

As shown in, when performing grinding operations in the preferred embodiment, each protrusionabuts the upper end of each riser block, with each riser blockbeing used to raise each protrusionso that each second light guidecan be positioned axially at a virtual first position and such that the lower end of each second light guidedoes not extend beyond the lower surface of the abrasive cloth. As shown in, when installing or replacing the abrasive cloth, it is selected to cross each protrusionand each riser blockto abut the lower end of each protrusionagainst the upper end of each base, and the upper end of each riser blockagainst the lower surface of each bushing, thereby reducing the height of each bushingso that each second light guidecan be positioned axially at a virtual second position. At this time, the lower end of each second light guidefurther protrudes downward beyond the lower surface of the grinding diskto penetrate the multiple through-holesof the abrasive clothand guide the positioning of the abrasive cloth, thereby improving the convenience of installing the abrasive cloth.

The number of the protrusionsformed by each bushingmay vary as needed, but is limited to one protrusionformed on each bushing; the number of the riser blocksformed by each basemay vary as needed, but is limited to one riser blockformed on each base, and the number of the riser blocksis not less than the number of the protrusions.

Each bushingforms a gapalong its radial direction, and each gapextends to the radial outer periphery and the radial inner periphery of each bushing. Each bushingis screwed with a second fastening boltalong its radial direction to reduce the width of the gapand to tighten the radial inner periphery of the bushingso that the bushingcan tightly adhere to the radial outer periphery of each second light guide, thereby increasing the bonding strength between each bushingand each second light guide.

Each of the second positioning structuresalso includes two second positioning bolts. Each of the second positioning boltsis pivotally threaded through each baseand screwed into the grinding diskto lock each baseto the grinding disk, thereby increasing the stability of each second positioning structurein positioning on the grinding disk.

On each of the second light guides, a first grooveand a second grooveare formed and spaced axially along the radial outer periphery of the second light guides, wherein the first grooveand the second grooveare circularly surrounded along the radial outer periphery of each of the second light guidesto form a ring shape. Each of the second positioning structuresfurther includes a set screw, each of which is radially screwed into each of the bases. When each of the second light guidesis positioned at the first position, each of the set screwsenters the first groove, respectively. When each of the second light guidesis to be moved downward and positioned at the second position, each of the set screwsis rotated to come out of the first groove, respectively. After each of the second light guidesis positioned at the second position, each of the set screwsis further rotated to enter the second groove, respectively, wherein each of the set screwsis used to increase the stability of each of the second light guidesin positioning at the first position or the second position.

Each of the second positioning structuresfurther includes two connecting bolts. Each of the connecting boltsis sequentially axially connected and composed of a head, a connecting rod section, and a screw section.

When each second light guideis positioned at the first position, each screw sectionis threaded through each bushingand screwed into each riser block, and each headabuts the upper surface of each bushing, thereby increasing the positioning stability of each bushingrelative to each base, which will not be affected by the vibration generated during the grinding process, so that each second light guidecan be more stably positioned at the first position.

When the second light guideis axially positioned at the second position, each screw sectionexits from each riser blockand screws into each bushing, with each headdisengaging from the upper surface of each bushing, whereby, the connecting boltwill then not limit the operation of cross displacement between each protrusionand each riser block. When it is necessary to install or replace the abrasive cloth, each connecting boltwill still remain connected to each bushingduring the process of changing each second light guidefrom the first position to the second position, thereby preventing the loss of the connecting bolt.

Each of the first light guidesand each of the second light guidesrespectively forms two stoppers, each stopperbeing located on the lower surface of each light transmission plate, thereby positioning each light transmission plate; the number of stoppersmay vary as needed, but each of the first light guidesand each of the second light guidesrespectively is provided with at least one stopperin principle.