JPH084079B2 - Mirror-polished compound semiconductor rectangular wafer manufacturing method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for producing a mirror-polished semiconductor rectangular wafer, and in particular eliminates the need for a final organic solvent wash conventionally required for such wafer production. The present invention relates to a method for producing a mirror-polished semiconductor rectangular wafer capable of producing a rectangular semiconductor wafer having a slight edge.

The present invention is directed to compound semiconductors including III-V group compound semiconductors such as GaAs, InP and GaP and II-VI group compound semiconductors such as ZnSe and CdTe, and is particularly used as a substrate for liquid phase epitaxial growth. It is useful for manufacturing compound semiconductor rectangular wafers.

BACKGROUND OF THE INVENTION Semiconductor wafers include a slicing step for slicing a single crystal ingot to an appropriate thickness, an etching step, a lapping step for smoothing the surface of the generated slice, an etching step for removing a work-affected layer caused by lapping, and the like. It is manufactured by finishing it to a mirror surface by mirror polishing and then subjecting it to a washing and drying process, especially when a compound semiconductor wafer is used as a substrate for liquid phase epitaxial growth. Cleave.

Conventional technology and its problems When manufacturing a mirror-polished rectangular wafer, the manufacturing process is such that after slicing and etching a single crystal, The following flow is commonly used. In the above process,
The main purpose of the organic cleaning step immediately after the secondary mirror polishing step is to remove the wax used for wafer bonding. The main purpose of water-based cleaning is to remove fine particles adhering to the wafer.

Although a clean rectangular wafer can be obtained by this method, the following problems have been newly recognized: (i) After secondary mirror polishing, organic and aqueous cleaning are performed, and thereafter, Since the rectangular cleavage is performed, recontamination of the wafer occurs due to the fragments of the substrate generated during the handling and the cleavage operation. As seen in InP compound semiconductors, most common compound semiconductors are hydrophilic immediately after polishing, but then become hydrophobic within a few days due to natural oxidation. Since the rectangular cleavage is usually performed several days after polishing, the surface is hydrophobic. For this reason,
The organic cleaning is more effective than the aqueous cleaning in order to sufficiently remove the substrate fragments and other contaminants. Therefore, as described above, a final organic cleaning was required. However, in the end, since the organic cleaning is performed twice after the secondary mirror polishing and the final cleaning, a large process load is imposed. In many cases, the final organic cleaning is carried out by the user side, which places a burden on the user side.

(Ii) When handling a rectangular wafer, chipping of its edge is likely to occur.

SUMMARY OF THE INVENTION In order to solve these problems, the inventors of the present invention have conducted a comprehensive study of the conventional rectangular wafer manufacturing process, and as a result, the rectangular cleavage process is performed between the primary mirror polishing process and the secondary mirror polishing process. I realized that these problems could be solved all at once by simply moving them forward. To divide into (i) to (ii), with respect to (i), in the case of a cleaved rectangular wafer, secondary mirror polishing can be performed by using an appropriate jig without using wax. It has been found that this secondary mirror-polished wafer can be sufficiently removed of contaminants by water-based cleaning. When a large primary mirror-polished wafer is directly subjected to secondary mirror-polished, wax attachment is necessary.
The final organic cleaning can be omitted by subjecting the small rectangular wafer after cleavage to the secondary mirror polishing. The root cause of the problem (ii) is that the peripheral edge of the rectangular wafer is sharp, and thus chipping is triggered even by a very slight contact. Therefore, a blunted ridgeline can be obtained by intentionally introducing the drool, and it can be effectively used for chipping suppression.

Thus, the present invention intentionally introduces a fringe, which has hitherto been overlooked as an unavoidable occurrence, into each rectangular wafer, thereby positively utilizing it as a chipping prevention means, and at the same time, in the final organic system. It succeeded in eliminating the washing step.

Thus, the present invention, organic compound cleaning and rectangular cleavage or rectangular cleavage and organic cleaning of the compound semiconductor wafer that has been subjected to slicing, lapping, etching and primary mirror polishing, and then the cleavage of the rectangular wafer surface (front. ) Surface is subjected to secondary mirror polishing, and finally is subjected to aqueous cleaning, to provide a method for producing a mirror-polished compound semiconductor rectangular wafer.

Although it is conceivable to perform the rectangular cleavage step before the primary mirror polishing as a method for forming the rim, in this case, the rim is too large and cannot be an obstacle to the epitaxial growth on the wafer. According to the method of the present invention, the rim is small, and the epitaxial growth can be further improved.

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to compound semiconductors such as III-V compound semiconductors and II-VI compound semiconductors. Recently, Ca has recently been used for device purposes such as semiconductor lasers, light-emitting elements, and light modulators.
Many As and InP rectangular wafers are used as substrates for crystal growth by epitaxial growth. GaAlAs / GaAs, GaAsP / GaAs, GaInAs / GaAs, InGaAsP /
InP is an example. In addition, it can be applied to CaP, ZnSe, CdTa and the like.

According to the present invention, the semiconductor wafer is mirror-finished by primary mirror-polishing after passing through the conventional single-crystal ingot manufacturing process, slicing process, etching process, lapping process and etching process. After this, the rectangular cleaving process which has been carried out lastly is carried forward and carried out first. After the organic cleaning, the rectangular cleavage may be performed, or conversely, the organic cleaning may be performed after the rectangular cleavage. After this,
A rectangular wafer is obtained by subjecting the cleaved individual wafers to secondary mirror polishing and hydrogen cleaning.

The above flow is as follows: Etching after the slicing step is mainly intended for pre-smoothing to remove rough surfaces by slicing, and etching after the lapping step is intended for removing the work-affected layer by lapping.

The wafer that has been subjected to primary mirror polishing is first subjected to an organic cleaning using an organic solvent such as trichloroethylene, ketone, alcohol, etc., and then cleaved into a rectangular wafer of a predetermined size, or the order is reversed to form a rectangular wafer. After cleaving the wafer, organic cleaning is performed. In the former case, the wax is completely removed from the wafer at the time of cleavage, so that the wafer has a constant thickness and the cleavage depth for cleavage becomes constant. Therefore, the cleavage yield is improved. On the other hand, there is a possibility that the adhered substances on the back surface remaining before the secondary mirror polishing cannot be completely removed. In the latter case, since the organic cleaning is performed later, the contaminants can be completely removed, but the scratch depth for cleavage may not be constant.

The rectangular wafer thus produced is subjected to a secondary mirror polishing step. The secondary mirror polishing is performed using an appropriate jig that can be attached to the base after polishing without using wax. For example, such a jig generally called a template is commercially available. The rectangular wafer is placed in the loading hole of the jig template and fixed to the base by frictional force. This non-wax type single-sided mirror polishing machine has not been used so far, because the back surface may be discolored when a polishing solution with a strong chemical action is used. As in the case of the invention, when only a short time polishing is performed with a gap from the primary mirror surface polishing, the back surface discoloration does not occur, and it has been found that it can be used.

In the secondary mirror polishing at this stage, the processing accuracy has already been obtained by the primary mirror polishing, so the surface can be finished to a very good mirror surface. Moreover, it causes slight fringes on the surface of each rectangular wafer. Of course, this drool is mild enough that it does not affect the final fabricated device. In addition, the formation of the edge drastically reduces the chipping that often occurs when the sharp edge angle of the wafer comes into contact with the object during conventional handling.

Finally, the rectangular wafer is cleaned using pure water having a specific resistance of about 17-18 MΩ · cm.

Contamination generated in the rectangular cleavage process is completely removed by the subsequent secondary mirror polishing-water cleaning process or by the organic cleaning-secondary mirror polishing-water cleaning process, and the surface after the secondary mirror polishing is hydrophilic. Since the water-based cleaning is performed in the meantime, contaminants can be effectively removed. Thus, the final organic wash is eliminated.

Advantageous Effects of Invention 1. Conventional final organic cleaning can be omitted without deteriorating the final surface cleanliness of a rectangular wafer.

2. Prevents chipping and greatly improves product yield.

Example 2 "φ pulled up by the liquid sealed Czochralski method
InP (100) single crystal is cut into a 0.5 mm thick wafer, and etching, double-sided lapping and etching are performed by the conventional method, and the etching wafer is further processed using a bromide-based polishing agent using a mirror polishing machine. Polishing was performed at a pressure of 100 g / cm ² for 60 minutes.

This wafer was washed with trichlene, acetone, and methanol, and then cleaved into a rectangle of 20 mm × 25 mm, and polished for 20 minutes at a processing pressure of 80 g / cm ² using a brominated polishing agent with a mirror polishing machine. Then, only the surface was polished by 5 μm.
Then, it was washed with pure water. By this process, the contamination generated during the cleavage of the rectangle was completely removed. Also, chipping could be drastically reduced.

Comparative Example A wafer that had been subjected to primary mirror polishing in the same manner as in Example 1 was subsequently subjected to secondary mirror polishing under the same conditions. Then Triclen,
Wash the adhesive wax with acetone and methanol.
After that, fine particles adhering to the wafer were removed by aqueous cleaning. After that, the wafer was cleaved into a rectangle of 20 mm × 25 mm, but the surface cleanliness was incomplete due to the powder of InP generated during cleavage and the contaminants attached during handling.
In order to remove this contaminant, further washing with an organic solvent such as trichlene, acetone and methanol was necessary.

Claims (1)

[Claims] 1. A compound semiconductor wafer subjected to slicing, lapping, etching and primary mirror polishing is subjected to organic cleaning and rectangular cleavage, or rectangular cleavage and organic cleaning, and then to the front surface of the cleavage rectangular wafer. A method for producing a mirror-polished compound semiconductor rectangular wafer, which comprises performing secondary mirror-polishing and finally performing an aqueous cleaning.