JPS58110499A - Specular etching method for wafer and wafer holder used for said method - Google Patents

Abstract

PURPOSE:To prevent the damage of wafers and to treat many sheets of wafers simultaneously by moving the wafers held in a wafer holder of cassette type together with the holder during the respective stages of specular etching treatments. CONSTITUTION:Wafers 10 are disposed on a wafer holder 1 consisting of a plate-like body 1 which has a recess 5 provided with a sharp-pointed projection 13 at the center in the bottom wall part and is formed with many through-holes 7 and water discharge holes 9, in such a way that orientation flats 10A ride on the projection 13. A large number of such holders 1 are contained in a multilayered case 20 having a prescribed number of perforated shelves 21 and are immersed in the etching soln. in a vessel 30 to etch the wafers; thereafter, the etching soln. is diluted with water. The case 20 is removed from the vessel 30, and the operator draws out the holders 1 by holding the handles 3 of the holders 1. After dewatering the wafers, the operator fits the projections 11 of the holders 1 into approximately semispherical hollow grooves 41 of drying jigs and lays the holders 1 toward a beaker 50 to dry the holders; thereafter, the operator lays the holders on a surface 43 and slightly raises the holders 1, thereby drying 1' the same.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to the use of gallium-arsenide (GaAs)-based MFs in the production of, for example, field effect transistors.
The present invention relates to a mirror finishing (mirror etching) method as a pre-process for growing an epitaxial layer (TFI) on a wafer, and a cassette type wafer holder used in the process.

(2) Background of the Technology In recent years, for example, gallium-arsenide (GaAs) substrates have been used instead of silicon (81) substrates as semiconductor material substrates (wafers) for forming semiconductor devices.

Since the substrate surface must be free of defects such as scratches, a mirror etching process is performed on the crystal growth surface of the wafer as a pre-expanding process. This mirror finishing and etching are finished by chemically etching the mechanically polished wafer by soaking it in an acid or alkaline solution, but the process includes a process of degreasing the wafer substrate prior to chemical etching, and the end of the chemical etching. Afterwards, a step of washing the wafer with water and finally a step of drying it are required.

(3) Problem 81 of conventional technology The wafer processing technology for substrates is now
When trying to apply it to a circuit board, the following problems arise.

1. 0am 1 is a stretchable round from the wafer,
! Although it is advantageous when cutting out a wafer, it is undesirable to grasp the wafer in a single position, which may cause cracking.

2.0aAs is moderately soft compared to the s content and is crystalline compared to the rounded 81 substrate, which is brittle. In the ninth step, stirring work during cinder becomes difficult. In other words, in the case of 81 wafers, automation and mass production have progressed, and manual wafer handling operations can be replaced by machines, but Ga is extremely fragile.
In the case of 1i1 wafers, such a method cannot be adopted.

3. Since 0aAm is highly chemically reactive, it cannot be exposed to high heat, and therefore, it cannot be drained and dried in a high-temperature atmosphere.

4. Due to the above-mentioned problems, a high degree of skill and extreme caution are required for the work, and it is extremely difficult to process a large number of wafers at once.

(4) Purpose of the Invention The purpose of the present invention is to solve the above-mentioned problems by using a cassette type wafer holder so that the movement of the wafer during processing can be done without having to hold the wafer with filigree tweezers, etc. Perform this with the wafer holder.
The object of the present invention is to prevent cracking or chipping of the wafer, and to enable simultaneous processing of a large number of wafers, thereby greatly reducing the number of man-hours in the pretreatment process for vapor phase growth.

(5) Structure of the invention: The wafer is held in a cassette-type wafer holder, and the substrate wafer is held in a cassette-type wafer holder. ! However, when moving the wafer during each process in the cutting process, the wafer holder can be moved without directly holding the wafer.

The wafer holder has four concave grooves for receiving the wafer (approximately circular in shape), and a pointed protrusion is formed on the bottom wall of the concave groove to support the wafer substantially at a point or in a line.

(6) Embodiments of the Invention As shown in FIG. It has a pointed protrusion 13 in the center, and the main body l has a symmetrical shape with this protrusion 13 as the center. The inverted V-shaped apex of the protrusion 13 may be a point or a line.Glyphs f3 are formed at both ends of the main body l, and the glyphs f3 are held by hand when moving the holder. A large number of through-holes 7 are formed in the main body l, allowing the flow of the tinda liquid. The through hole 7 may also be formed in the plate surface of the recess 5.

When the wafer 10 is submerged in the etching solution together with the holder, the etching solution can enter the container into the back side of the wafer IO, and when the wafer 10 is removed from the holder, the wafer IO and the plate of the recess 5 are arranged. In order to reduce the adhesion force with the surface, it is preferable that the recess 5 is a groove as shown in the drawing.

For example, the wafer 10 has its orientation
(OF) Place the IOA on the protrusion 13 and place it in the recess 5.
be located within. Thus, the wafer 10 will actually be held in a two-point support position against either side wall of the recess 5, rather than in a single-point support position as shown in FIG. A drainage hole 9 communicating with the recess 5 is formed at the bottom of the main body 1 at the protrusion 13. A pair of substantially spherical protrusions 11, for example, are provided at the bottom of the reed body l. These protrusions 11 are fitted into corresponding grooves of a drying jig, which will be described later.

The wafer holder 1 is housed in a multilayer case 20 as shown in FIG. The multilayer case 20 has a predetermined number of porous shelves 21t, and a wafer holder 1 is placed on each of these shelves 721, respectively. The case 20 has a handle 25, which serves as a handle during movement. Porous holes are also formed in the top plate and bottom plate of the case 20. Porous holes may also be formed in the side plate of the case 20. The case 20 is made of, for example, Teflon. Case 200 top and bottom plate, side plate and shell 22
1 may be a simple frame or framework instead of a plate, in which case no holes are required. The interval between the shelves 21 may be large enough to accommodate the holder l having the wafer 10, and the shape of the case 20 is not limited to the rectangular parallelepiped shown, but may be a cylinder or a polygonal prism.

Next, a method for performing mirror polishing and chiming using the Ueno-holder and case as described above will be explained.

Wafer, wafer holder, case and force (described later)
is degreased and cleaned in advance using an organic solvent such as Triflet. Etching liquid (e.g. H, 804-N
20. -1f20 series). The wafer 10 is supported in the recess 5 of the wafer holder 1 and placed on each shelf 21 of the case 20 in good condition. At this time, the mirror wafer 10 is placed so that the mirror surface side faces up. Next, the case 20 is immersed in an etching solution with a peel strength of 30 while holding the handle 25 (Fig. W44). Stir in the etching solution for a specified period of time (shake pressure), then pour a large amount of water into the beaker.
(Figure 5). At this time, it is important to wash the wafer with water by diluting the etching solution with a large amount of water, rather than opening the etching solution and then pouring water to prevent the wafer from coming into contact with the air. At this time, even if you pour water from the large lid all at once, there is no worry that the wafer will break because it is housed in the case 20. Also, when diluting the etching solution with a large amount of water, if you tilt the wafer holder so that it is aligned with the back side of the case L as shown in Figure 5, there is no need to worry about the wafer falling out of the case, and there is no risk of damage. It disappears.

When the water washing is completed, the material 20 is taken out from the beer force 30, and each wafer is taken out one by one from the case 20 together with the wafer holder. At this time as well, there is no need to directly grasp the wafer, just use the handle 3 of the holder l and pull out the wafer holder.The wafer IO is supported by the protrusion 13 in the recess 5 of the wafer holder l, so it sticks to the wafer lO. The water will flow into the acid part of the recess 5 and collect there. This accumulated water is discharged from the holder l to the outside through the drainage hole 9. That is, the wafer 10 can be drained while being held in the wafer holder 1.Finally, the wafer 10 is dried. For drying, a dryer X40 as shown in FIG. 6 is used.

The jig 40 has approximately hemispherical recesses 1141 that fit into the protrusions 11 of the wafer holder 1, and when the protrusions 11 of the wafer holder 1 are fitted into these grooves 41, the wafer holder uses these protrusions 11 as pivot points. As shown by the arrow in FIG. 7, there is a pivoting motion. The jig 40 has 9 surfaces 43 on which the wafer 10 leans, and 9 inclined surfaces 4s on which the dripping log falls.
and has.

When using Jiji II 40, it is convenient to use a wide-mouth pip force 50 as shown in FIG.

87 to dry the mirror-finished side of the wafer lO
As shown in the figure, the wafer holder 1 is placed against the bead force 50 so that the mirror surface side of the wafer 10 held on the wafer holder 1 faces upward. For example, nitrogen (N2) gas from an air gun 60 is used for drying. wafer l
After the mirror surface side of the O is completely dried, the holder 1 is raised around the protrusion 11 toward the leaning surface 43 of the holder 40.

When holder 1 rotates further beyond the upright position, the wafer l
The O comes off from the recess 5 of the holder 1 and is placed on the resting surface 43 of the old hood 40. At this time, the lower end of the wafer lO remains on the protrusion 13 of the holder 1. Therefore, by slightly returning the holder 1t-1' as shown by holder 1t-1', the back side of the wafer 10 will be exposed, so that nitrogen (N2) gas can be blown onto the back side of the wafer 10 using the air gas/60 for recording.

In this way, the one-sided processing and the chipping process are completely completed, and at this time the wafer IO is pinched with tweezers etc. for the first time and sent to the subsequent epitaxial vapor phase growth process.In the present invention, the wafer IO is completely dried. Since it was taken out from the holder, I used vacuum suction. pince,
can be used.

If the jig 40 has a symmetrical shape as shown in FIG. 6, two wafers can be dried at the same time.

(7) Effects of the Invention As described above, according to the present invention, the wafer is always moved along with the wafer holder throughout the mirror etching process, so all of the problems with the image quality mentioned at the beginning are solved. Further, according to the present invention, a large number of wafers can be processed simultaneously (i.e., wafer processing), so that work efficiency is greatly improved.

Furthermore, in the present invention, since the wafer can be taken out from the wafer holder in a completely dry state using vacuum tweezers or the like, wet sea urchins/1- can be removed from the wet wafer using a spindle, which is conventionally used in the Mizukiri-sho drying process. It is possible to eliminate the process of placing the product on the 9-Ever rotary table.

[Brief explanation of the drawing]

Figure s1 is a front view of the Uni-No-Holder according to the present invention, the second
The figure is a side view of Figure 1, and Figure 3 is a queharnel that is made of river sand in the present invention! , : Perspective view of the case, Figure 4 is a diagram showing the work, tick/tick process, Figure 5 is a diagram showing the washing process, Figure 6 is a diagram showing the washing process.
The figure is a perspective view of the drying oil ^, and Figure 7 is a diagram showing the dryer S. DESCRIPTION OF SYMBOLS 1...Holder body, 5...Concave fi, 10...Wafer, 13...Protrusion, 20...Case, 40...
Drying jig, 60...Airga/. Patent Applicant: Fujitsu Limited Patent Attorney: Akira Minori, Patent Attorney: Kazuyuki Nishidate, Patent Attorney: 1) Yukio, Patent Attorney: Akiyuki Yamaguchi Figure 4 Figure 5 Figure 7 = 611

Claims (1)

[Scope of Claims] 1. A process in which a degreased and cleaned wafer is immersed in a processing solution, and a wafer is immersed in a processing solution.
#-1 In the mirror etching process of wafers, the wafer is diluted with water, the wafer is removed, the water is drained, and the surface of the wafer is dried.The wafer is held by a cassette-type wafer holder. , wafer transfer during each of the above steps! A wafer mirror painting and chipping method is characterized by moving the entire wafer holder without directly gripping the wafer. 2. A wafer holder having a substantially circular recess for receiving a wafer and having a pointed protrusion formed on the bottom wall of the recess to support the wafer substantially at a point or a point.