JP3401975B2 - Dicing method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of dicing a wafer used in a dicing process for manufacturing a semiconductor device. 2. Description of the Related Art Conventionally, a wafer dicing apparatus includes a mounting table for mounting a wafer, and a disk-shaped rotary cutting device called a so-called dicer blade, which is set up and down on the upper surface side of the mounting table. And a blade (hereinafter, referred to as a cutting blade). The mounting table and the cutting blade have conductivity, and the mounting table and the cutting blade are connected to a detecting unit for detecting a conduction state between the mounting table and the cutting blade. In wafer dicing using such an apparatus, before the wafer is placed on the mounting table, the cutting blade is first lowered to detect the contact between the mounting table and the cutting blade by the detection means. The position of the blade is set as a reference position of the cutting blade. That is, the upper surface position of the mounting table is set as the reference position of the cutting blade. Then, a cut depth is designated by cutting without leaving the reference position, and the wafer is cut based on the designation. [0003] However, as described above, in the conventional dicing apparatus and dicing method, the cutting depth is specified by the amount of the cutting blade that is left uncut from the reference position. When setting the cut depth from the surface, the thickness of the wafer must be measured (or a predetermined value) in advance, and the remaining amount must be calculated and set from the value, which has been extremely complicated. In addition, since the reference position is set by bringing the cutting blade into contact with the mounting table, the upper surface of the mounting table is damaged, so that the thickness of the wafer apparently varies, and as a result, the cut depth varies. Was also awake. Furthermore, even when the thickness of the wafer itself varies, the cut depth from the wafer surface also varies. SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and a dicing method capable of cutting a wafer to a predetermined depth from the surface without damaging the mounting table, and which is easy to set the cut depth.
It is intended to provide law . SUMMARY OF THE INVENTION The present invention relates to a dicing method for cutting a wafer from a surface to a predetermined depth, wherein a conductive material is applied to the front, back, and side surfaces of the wafer to a thickness which does not affect the dicing. A step of processing the wafer so that it can conduct between the front and back, a step of mounting the wafer on a conductive mounting table, and a step of moving a conductive cutting blade from the front surface side of the wafer to the wafer and cutting the wafer. Detecting the conduction state between the blade and the mounting table, and setting the position of the cutting blade when the cutting blade and the mounting table are electrically connected via the wafer as a reference position; and Depth cutting step. In the dicing method of the present invention, a conductive material is applied to the front and back and side surfaces of the wafer to a thickness that does not affect dicing, and the wafer is processed so as to be able to conduct between the front and back. Then, after placing the wafer on the mounting table having conductivity, the conductive cutting blade is moved from the front surface side of the wafer to the wafer, and the conduction state between the cutting blade and the mounting table is detected. The reference position is set at the wafer surface position, since the position of the cutting blade at the time when the and the mounting table are conducted through the wafer is used as the reference position. Therefore, the wafer is cut at a predetermined depth from the surface. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing one embodiment of a dicing apparatus used in the dicing method of the present invention . The dicing apparatus 1 is for cutting the wafer 10 conducted between the front and back from the surface by a predetermined depth t, and has a conductive mounting table 2 on which the wafer 10 is mounted, and A disk-shaped cutting blade 3 installed on the mounting surface side of the wafer 10, that is, on the upper surface side, a driving unit 4 and a rotating mechanism 5 connected to the cutting blade 3, and between the cutting blade 3 and the mounting table 2. It comprises a detecting means 6 provided and a control means 7 connected to the detecting means 6, the driving means 4 and the rotating mechanism 5, respectively. The cutting blade 3 is made of, for example, metal and has conductivity, and is arranged so that its surface direction is substantially perpendicular to the upper surface (mounting surface) of the mounting table 2. Cutting blade 3
Can be moved in a direction substantially perpendicular to the upper surface of the mounting table 2 by driving of the driving means 4, that is, can be moved up and down. Further, the cutting blade 3 is configured to rotate around the center of the cutting blade 3 by driving of the rotation mechanism 5. The detecting means 6 is for detecting a point in time when the cutting blade 3 and the mounting table 2 are electrically connected via the wafer 10 mounted on the mounting table 2, and includes, for example, an ammeter and an ohmmeter. It is composed of Here, a power supply 8 is provided between the detection means 6 and the mounting table 2. Further, the control means 7 controls the driving means 4 based on the detection result from the detection means 6.
And the drive of the rotation mechanism 5 is controlled. In such a dicing apparatus 1,
Since the wafer 10 is conductive between the front and back and the mounting table 2 has conductivity, when the wafer 10 is mounted on the upper surface of the mounting table 2, the wafer 10 and the mounting table 2 are electrically connected. In addition,
The wafer 10 that is conductive between the front and back means a wafer that is conductive between the front and back surfaces of the wafer and that has conductive surfaces. Generally, a scribe line, which is a cut portion of the wafer 10, is a low-resistance diffusion layer, so that the wafer 10 is conductive between its front and back sides. Further, since the cutting blade 3 also has conductivity, when the cutting blade 3 comes into contact with the surface of the wafer 10 mounted on the mounting table 2, the cutting blade 3 and the mounting table 2 conduct through the wafer 10. I do. The conduction state, that is, the time point when the state changes from the non-conduction state to the conduction state, is detected by the detection means 6, and the detection result is sent to the control means 7. Then, the control means 7 sets the position of the cutting edge 3 at the time when the conduction is detected, that is, the surface position of the wafer 10 as a reference position of the cutting edge 3 when cutting the wafer 10, and a depth designated from this reference position. The drive of the drive mechanism 4 and the rotation mechanism 5 is controlled so as to perform cutting. Next, an embodiment of the dicing method according to claim 2 will be described by taking as an example a case where the wafer 10 is diced using such a dicing apparatus 1. First, the wafer 10 is mounted on the upper surface of the mounting table 2 and the rotating mechanism 5
And the driving means 4 drives the mounting table 2 for the wafer 10.
The cutting blade 3 is slowly lowered from the side opposite to the upper surface, that is, from above the wafer 10 while rotating. At this time, the detecting unit 6 detects the conduction state between the cutting blade 3 and the mounting table 2. Then, the cutting blade 3 comes into contact with the surface of the wafer 10,
The position of the cutting edge 3 (surface position of the wafer 10) at the time when the cutting edge 3 and the mounting table 2 are electrically connected via the wafer 10 is set as the reference position of the cutting edge 3 when cutting the wafer 10. Next, the cutting blade 3 is once raised, and the wafer 1
The cutting blade 3 is repositioned at the scribe line position of 0, and the cutting blade 3 is lowered while rotating again to cut the wafer 10 from the reference position to a predetermined depth. In this embodiment, the cut depth from the surface of the wafer 10 is specified as the specified cut depth. In this embodiment, the position of the surface of the wafer 10 is automatically detected, and the reference position of the cutting blade 3 for cutting the wafer 10 is set at the surface position of the wafer 10. The depth can be set as the designated cut depth from the reference position. FIG. 2 is a diagram illustrating a result of examining the relationship between the designated cut depth and the actual cut depth when the wafer 10 is cut according to the present embodiment. As shown in FIG. 2, according to the present embodiment, it can be seen that the designated cut depth is substantially equal to the actual cut depth. Therefore, in this embodiment,
When the wafer 10 is cut, the cut depth from the surface of the wafer 10 may be designated, so that the work of setting the cut depth can be performed very easily. Further, since the surface position of the wafer 10 is used as the reference position of the cutting blade 3, the wafer 10 can be cut by a predetermined depth t from the surface regardless of the variation in the thickness of the wafer 10. Further, when the reference position of the cutting blade 3 is set, the cutting blade 3 is not brought into contact with the mounting table 2, so that the upper surface of the mounting table 2 is not damaged. Therefore, according to this embodiment, the wafer 10 can be easily and accurately cut from the surface by a predetermined depth t. Therefore,
This is particularly effective in the process of forming a laser diode that performs a so-called half-cut process. If the scribe line of the wafer is not conducting between the front and back during dicing,
Before dicing, apply a conductive material to the front and back of the wafer and the side of the wafer to a thickness that does not affect dicing,
The wafer may be electrically connected between the front and back sides. Further, in a device manufacturing process of a wafer, for example, in a heat treatment step or the like, a conductive pattern for establishing conduction between the front and the back can be formed so that the wafer can be kept in a conductive state between the front and the back. As described above, the dicin of the present invention
In this method, a conductive material is applied to the front, back, and side surfaces of the wafer.
Apply to a thickness that does not affect icing, and
By processing to be conductive, the front and back of the wafer can be conductive
Conduction between the front and back of the wafer even if the wafer is not in a state
Can be done. Further, the position of the cutting blade at the time when the cutting blade and the mounting table are conducted through the wafer is set as the reference position of the cutting blade when cutting the wafer, and this reference position is set at the position of the wafer surface. The cut depth from the wafer surface may be the designated cut depth from the reference position,
The setting operation of the cutting depth can be performed very easily. Further, since the wafer surface position is used as the reference position of the cutting blade, the wafer can be cut to a predetermined depth regardless of the variation in the thickness of the wafer. Furthermore, when setting the reference position of the cutting blade, the cutting blade is not brought into contact with the mounting table, so that the upper surface of the mounting table is not damaged. Therefore, according to the present invention, it is possible to a predetermined depth cut easily and accurately wafer.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing one embodiment of a dicing apparatus used for a dicing method of the present invention . FIG. 2 is a graph showing a relationship between an actual cut depth and a designated cut depth. [Description of Signs] 1 Dicing apparatus 2 Mounting table 3 Cutting blade 4 Driving means 6 Detecting device 7 Control means 10 Wafer

Claims (1)

(57) [Claim 1] A dicing method for cutting a wafer from a surface to a predetermined depth, wherein a conductive substance is applied to the front, back, and side surfaces of the wafer to a thickness which does not affect dicing. A step of processing the wafer so that it can conduct between the front and back, a step of mounting the wafer on a mounting table having conductivity, and a step of moving a conductive cutting blade from the front surface side of the wafer to the wafer. A step of detecting a conduction state between the cutting blade and the mounting table, and setting a position of the cutting blade at a time when the cutting blade and the mounting table are conducted through the wafer as a reference position, and Cutting a predetermined depth from the reference position.