JPH05226308A - Method and equipment for processing rear surface of semiconductor wafer - Google Patents

Abstract

PURPOSE:To enable rear surface grinding for obtaining a semiconductor wafer having a specified thickness with high precision by using a fewer treatment processes. CONSTITUTION:After a semiconductor wafer 1 whose rear is protected with a protective tape 3 is subjected to rear grinding by a rough grindstone 12 and a finishing grindstone 14 of a rear processing equipment 10A, the wafer 1 is transferred to a spinner 15. A damage layer 4 generated in a semiconductor layer 1C is subjected to spin etching by using etching solution from a nozzle 20 for etching. After that, spinner cleaning and spinner drying are performed, and a semiconductor wafer having a specified thickness is obtained by a sheeting process. Since the batch processing is not used as in the case of a conventional technique, irregularity in each semiconductor wafer is little, high precision is obtained, manhour and cost are reduced, and the conventional rear processing equipment can be appropriated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of processing a back surface of a semiconductor wafer and an apparatus therefor for making the semiconductor wafer have a predetermined thickness.

[0002]

2. Description of the Related Art A conventional technique will be described with reference to FIGS. FIG. 3 is a sectional view of a semiconductor wafer for explaining a conventional method and a back surface processing method for a semiconductor wafer according to the present invention, FIG. 4 is a process diagram of a conventional back surface processing method for a semiconductor wafer, and FIG. 4 is a conceptual diagram of a semiconductor wafer back surface processing apparatus used in the semiconductor wafer back surface processing method shown in FIG.

In order to make a semiconductor wafer having a semiconductor integrated circuit formed on its surface have a predetermined thickness, according to the prior art, as shown in FIG.
This is performed by the steps shown in FIG. That is, in order to thin the semiconductor wafer 1 having a thickness of, for example, 625 μm shown in FIG. 3A into the semiconductor wafer 1A having a thickness of, for example, 400 μm shown in FIG. 3C, first, the process shown in FIG. In step (1), the resist film 2 is applied to the surface of the semiconductor wafer 1, and in the next step (2), the protective tape 3 is attached.

In the next step (3), a plurality of semiconductor wafers 1 processed in this way are accommodated in a wafer carrier 21 and the semiconductor wafer back surface processing apparatus shown in FIG. Device) 10) to a carrier loader 18.

In addition to the carrier loader 18, the rear surface processing apparatus 10 includes a first rotating stage 11, a rotating coarse grindstone 12 arranged to face the first rotating stage 11, a second rotating stage 13 and the like. It is composed of a rotating finishing grindstone 14 arranged to face the same, a common spinner 15, a water injection nozzle 16 and an air nozzle 17 arranged to face the same, and a carrier unloader 19. .

The plurality of semiconductor wafers 1 carried into the carrier loader 18 are taken out one by one from the wafer carrier 21 and are fixed to the rotary stage 11 at the fixing place A, and the protective tape 3 is directed downward. Then, the semiconductor wafer 1 is fixed by vacuum suction, then rotated by 180 °, the back surface of the semiconductor wafer 1 is brought under the rough grindstone 12, and rough grinding is performed.

When the rough grinding is completed, the rotary stage 11 is rotated to the original position, and the rough-ground semiconductor wafer 1B is moved to the fixed position B of the rotary stage 13 in the next step (4). Instead, it is fixed by vacuum suction as in the previous step (3), and the rotating stage 13 is rotated 180 ° to bring the back surface of the semiconductor wafer 1B under the finishing grindstone 14 for finish grinding.

When the semiconductor wafer 1B is finish-ground to a substantially predetermined thickness, the rotary stage 13 is rotated to its original position, and the finish-ground semiconductor wafer 1C is transferred to the spinner 15, placed and rotated. While cleaning with pure water sprayed from the water injection nozzle 16 [step (5)], air is sprayed from the air nozzle 17 while rotating the spinner 15 as well to dry the semiconductor wafer 1C [step (6) )].

The semiconductor wafer 1 finish-ground in this way
As shown in FIG. 3B, the back surface, which is the ground surface of C, is cracked by a depth of about 1 μm by the mechanical grinding, and a damaged layer 4 is generated.

In order to remove the damage layer 4, a plurality of such semiconductor wafers 1C, a wafer carrier 21 are used.
3 and then, in the next step (7), immersing in the etching solution (for example, HF + HNO ₃ ) in the etching bath 30,
As shown in C, etching is performed to a thickness of about 5.5 μm.

When this chemical etching is completed, the wafer carrier 21 is placed in a plurality of water tanks 22 in the next step (8).
23, and the semiconductor wafer is washed with pure water. Then, for further finishing, the wafer is transferred to the bath 24 in the next step (9), light etching is carried out, and then again washed with pure water. The washing in this step (10) also includes a plurality of water tanks 25,
26.

A plurality of wafer carriers 21 accommodating such semiconductor wafers 1A are placed on a spin dryer 27 in the next step (11) to dry the water by centrifugal force. Thus, the 400 μ shown in FIG. 3C is obtained.
A semiconductor wafer 1A having a predetermined thickness of m and still having the protective tape 3 is obtained. The steps (7) to (11) are performed in a batch process.

Then, in the next step (12), the protective tape 3 is peeled off from the semiconductor wafer 1A by the protective tape peeling machine, and the resist film 2 is dissolved with a solvent. Through these steps, only the semiconductor wafer 1A having a predetermined thickness, which is the final purpose, is obtained.

[0014]

In order to eliminate the damage layer 4 generated in the semiconductor wafer 1C due to the backside grinding by the above-mentioned backside processing method of the prior art, a grindstone having small abrasive grains is used, and the backside of the semiconductor wafer 1C is removed. Although a method of eliminating the chemical etching has been attempted, the chemical etching of the back surface is inevitably necessary as the diameter of the semiconductor wafer becomes larger and the semiconductor chip becomes thinner.

However, in the chemical etching by the batch processing, the etching accuracy in the semiconductor wafer, in the batch, and between the batches is poor, and the number of working steps is large. The acid resistance of the protective tape is required, and such a protective tape is more expensive than general ones. This invention made it a subject to eliminate such a defect.

[0016]

Therefore, in the present invention, a protective tape is attached to the surface of a semiconductor wafer, the semiconductor wafer with the protective tape attached is attached to a stage from the protective tape side, and the back surface of the semiconductor wafer is attached. Is ground with a grinding wheel, then the back surface of the ground semiconductor wafer is chemically etched while rotating, and then the chemically etched semiconductor wafer is rotated and washed with pure water, and further cleaned. A method of obtaining a semiconductor wafer having a desired thickness by blowing air while rotating the semiconductor wafer was dried. As an apparatus embodying this method for processing the back surface of a semiconductor wafer, a first rotary stage, a rotary grinding stone for rough grinding arranged facing the first rotary stage, and a second rotary stage arranged to face the second rotary stage. It was composed of a finish grinding grindstone, a common spinner, and an etching nozzle, a pure water nozzle and an air nozzle which were arranged to face the common spinner.

[0017]

Therefore, according to the semiconductor wafer back surface processing method and apparatus of the present invention, there is no variation in chemical etching between semiconductor wafers due to batch processing, and since each wafer is processed, each semiconductor wafer is etched. You can check the surface.

[0018]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 3. FIG. 1 is a process diagram for explaining a semiconductor wafer back surface processing method of the present invention, and FIG. 2 is a conceptual diagram of a back surface processing apparatus used in the semiconductor wafer back surface processing method of the present invention. The same steps and devices as those of the prior art shown in FIGS. 4 and 5 are designated by the same reference numerals, and the description of their configurations and functions will be omitted.

FIG. 2 shows a semiconductor wafer backside processing apparatus (hereinafter simply referred to as "backside processing apparatus") 10A of the present invention. A portion different from the conventional back surface processing apparatus 10 shown in FIG. 5 faces the spinner 15, and a water injection nozzle 16 is provided.
In addition to the air nozzle 17, the etching device including the etching nozzle 20 is provided. In addition, a device and a recovery device for preventing the scattering of the etching liquid sprayed from the etching nozzle 20 are installed.
Although they are not essential to the present invention, they are omitted, but other configurations are the same as those of the conventional back surface processing apparatus 10 shown in FIG.

By installing the etching apparatus including the etching nozzle 20 in the back surface processing apparatus 10,
As shown in FIG. 1, the back surface processing method for a semiconductor wafer according to the present invention can greatly simplify the processing steps.

In the backside processing step diagram of FIG. 1, steps (1) to (4) and step (12) are the same as the steps in the backside processing step of FIG. The semiconductor wafer 1C finish-ground in the step (4) is transferred from the fixing place B of the rotating stage 13 to the spinner 15 in the next step (13) and placed. Then, while rotating the semiconductor wafer 1C, first, on the back surface thereof, the etching nozzle 2 is formed.
An etching liquid is jetted from 0 to etch the damage layer 4 on the back surface of the semiconductor wafer 1C as shown in FIG. 3B.

When the damaged layer 4 is removed from the semiconductor wafer 1C to a predetermined thickness, the jetting of the etching solution is stopped, and then the same spinner is used to perform the next step (14) of pure water cleaning. Pure water is sprayed from a water injection nozzle 16 while rotating the semiconductor wafer 1A at 15. This step (14) corresponds to the step (10) in the conventional technique of FIG. 4, and is not the pure water cleaning step of the step (5).

Next, air is jetted from the air nozzle 17 while being rotated by the spinner 15 as well to dry the water adhering to the semiconductor wafer 1A by centrifugal force and air [step (15)]. This step (15) is a step corresponding to the step (11) in the conventional technique of FIG. 4, and is different from the spinner drying step of the step (6).

Then, in the same protective tape peeling step (12) as the conventional step (12) in FIG. 4, the protective tape 3 is peeled off from the semiconductor wafer 1A by the protective tape peeling machine to remove the resist film 2 from the solvent. Then, the semiconductor wafer 1A having a predetermined thickness, which is the final purpose, is obtained.

[0025]

As described above, the semiconductor wafer back surface processing method of the present invention eliminates the variation in chemical etching of semiconductor wafers due to batch processing, which has been found in the prior art, and provides a highly accurate semiconductor wafer. Obtainable. Then, because of the leaf-by-leaf processing, it is possible to confirm the etching surface for each semiconductor wafer. Moreover, since the treatment process can be significantly simplified as compared with the treatment process of the conventional technique, the number of steps can be reduced, and accordingly, the semiconductor chip can be manufactured at low cost, which is an excellent effect.
Also, the semiconductor wafer back surface processing apparatus of the present invention can be used as a conventional back surface processing apparatus only by adding an etching processing apparatus, and it is not necessary to make an excessive capital investment. It has an excellent effect that it can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a process drawing of a back surface processing method for a semiconductor wafer according to the present invention.

FIG. 2 is a conceptual diagram of a semiconductor wafer back surface processing apparatus of the present invention.

FIG. 3 is a cross-sectional view of a partial semiconductor wafer used for explaining the method of processing the back surface of a semiconductor wafer and the apparatus therefor according to the present invention.

FIG. 4 is a process diagram of a conventional semiconductor wafer back surface processing method.

FIG. 5 is a conceptual diagram of a conventional semiconductor wafer back surface processing apparatus.

[Explanation of symbols]

 1 Semiconductor Wafer 2 Reegist Film 3 Protective Tape 10A Semiconductor Wafer Backside Processing Device 11 Stage 12 Rough Grinding Stone 13 Stage 14 Finishing Grinding Stone 15 Spinner 16 Water Injection Nozzle 17 Air Nozzle 20 Etching Nozzle

Claims (2)

[Claims] 1. A protective tape is attached to the surface of a semiconductor wafer,
The semiconductor wafer to which the protective tape is attached is attached to the stage from the protective tape side, the back surface of the semiconductor wafer is ground with a grinding wheel, and then the back surface is chemically etched while rotating the ground semiconductor wafer. After that, the chemically etched semiconductor wafer is washed with pure water while rotating, and the washed semiconductor wafer is further rotated by blowing air to obtain a semiconductor wafer having a desired thickness. Semiconductor wafer backside processing method. 2. A common first rotary stage, a rough grinding rotary grindstone arranged opposite to the first rotary stage, and a second rotary stage common to a finish grinding grindstone arranged opposite thereto. A spinner and an etching nozzle arranged opposite to the spinner;
A backside processing apparatus for a semiconductor wafer, comprising a pure water nozzle and an air nozzle.