JP2959384B2 - High strength stainless steel sheet for ID blade and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention mainly relates to Si, Ga
Ultra-thin inner peripheral blade cutter (Inner diameter) for cutting a semiconductor single crystal ingot such as As into a wafer shape
The present invention relates to a high-strength stainless steel sheet used for a substrate and a method for producing the same.

[0002]

2. Description of the Related Art In wafer processing of semiconductor materials such as Si and GaAs, it is required that the cutting loss of an ingot to be cut be minimized as much as possible, and that the wafer obtained by cutting be flat, smooth and free from distortion. You.

In particular, the demand for flatness has become strict with the recent ultra-high integration of ICs. For example, in a 4M device, the flatness is 0.8 μm / 15 × 15 mm ² because the processing line width of the wafer is 0.7 to 0.8 μm, and in a 16M device, the flatness is 0.5 μm because the processing line width is 0.5 μm. 5 μm / 20 × 20 mm ² is required.

[0004] Accordingly, the material used for the ID blade also has high plate thickness accuracy and flatness, high strength for withstanding cutting by repeated high-speed rotation, and high rigidity for reducing the vibration width generated during cutting. Is required. In order to satisfy these demands, in the production of the material for the ID blade substrate, high-precision multi-stage reversing mill rolling can be performed, and furthermore, the flatness and thickness accuracy in the plane can be improved by applying tension annealing. Is planned.

[0005]

However, the accuracy of the thickness of the wafer and the macroscopic shape (warp, middle elongation, etc.) are being improved by the above-described manufacturing method, but the integration is increasing. In the cutting of IC wafers, there is a problem that it is difficult to say that sufficient surface accuracy is obtained even at present, and the surface accuracy (warp, flaw, etc.) of the wafer after the mirror finishing process after cutting is poor. Many cases of failure have been reported.

This is because, during cutting, cutting chips remain on the ID blade surface and damage the surface to be cut, or the distortion applied to the wafer is large, so that sufficient smoothness and flatness cannot be obtained. is there. In particular, when the degree of integration is 4 Mbits or more, there is a problem that it is unavoidable that the failure rate is extremely high.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems of the prior art, and it is an object of the present invention to reduce the loss due to poor cutting of a material to be cut and to provide excellent surface accuracy to a surface to be cut. It is an object of the present invention to provide a high-strength stainless steel sheet and a method for producing the same.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a small loss due to defective cutting of a surface to be cut and provides excellent surface accuracy to the surface to be cut. SUMMARY OF THE INVENTION An object of the present invention is to provide a high-strength stainless steel sheet and a method for producing the same, which are summarized as follows: (1) The center line average roughness (Ra) of the surface is 0.02 to 0.
20 μm, the maximum roughness (Rmax) is 2.0 μm or less, the average distance between irregularities (RSm) is 50 μm or more, and the index (Rsk) of deviation in the height direction of the roughness curve is +1.5 or less. High strength stainless steel sheet for ID blade.

(2) The martensite phase in the ID blade material is 40 to 95 vol. %, With the balance being substantially austenitic. (3) A method for producing the high-strength stainless steel sheet, comprising a step of producing a steel strip, a step of annealing and cold rolling, and a step of low-temperature heat treatment. The low-temperature heat treatment after annealing and finish rolling was performed at 70 vol. %, Wherein the finish rolling is performed using a bright roll to a total rolling reduction of 50 to 76%.

[0010]

As a method for solving the above problems, I
It is effective to control the surface properties in addition to the shape and thickness accuracy of the D blade substrate material. That is, by optimizing the roughness of the surface of the material, it is possible to suppress cutting chips from remaining on the blade surface during cutting, and to improve the lubricity of cutting, thereby substantially reducing scratches and distortion given to the wafer surface. As a result, a wafer with extremely excellent surface accuracy can be obtained.

The reason why the constituent elements of the stainless steel sheet according to the present invention are limited will be described below. In order to obtain a surface to be cut having excellent surface accuracy as intended in the present invention, control of the surface texture is most important. With respect to the surface properties, the present inventors paid particular attention to center line average roughness (Ra), maximum roughness (Rmax), average distance between irregularities (RSm), and index of deviation of roughness curve (Rsk). There are four parameters. When these values were changed in various ways, the relationship between them and the wafer failure rate was investigated. It has been found that a wafer having excellent surface accuracy can be produced by controlling the above parameters within a specific range.

The reasons for the limitation will be described below. (1) Center Line Average Roughness (Ra) Ra is the center line average roughness and is represented by the following equation (1).

[0013]

(Equation 1)

However, L: measured length, f (x): roughness curve If Ra is less than 0.02 μm, strong friction occurs between the workpiece and the workpiece during cutting, causing excessive distortion on the workpiece surface. Deterioration of the given surface accuracy. On the other hand, if it exceeds 0.20 μm, it becomes difficult for the cutting chips to be collected and removed from the surface of the ID blade during the cutting, and the surface accuracy of the surface to be cut is deteriorated. Therefore, Ra was set to 0.02 to 0.20 μm.

(2) Maximum roughness (Rmax) The maximum roughness (Rmax) is a vertical distance between a maximum peak and a maximum valley with respect to a line parallel to the center line in the roughness curve.
If Rmax exceeds 2.0 μm, cutting chips will be generated during cutting.
Since it is difficult to discharge the pool between the unevenness of the blade surface and the outside of the pool, the surface accuracy of the cut surface is deteriorated. Therefore, Rmax
Was 2.0 μm or less.

(3) Average distance between irregularities (RSm) The average distance between irregularities (RSm) is expressed by the following equation (2).

[0017]

(Equation 2)

However, RSmn: from the point where the curve from the n-th peak (convex portion) to the valley (concave portion) crosses the center line, (n
-1) If the distance of the first point, RSm, is less than 50 μm, the cutting chips will be ID during cutting.
Since it is difficult to discharge the pool between the unevenness of the blade surface and the outside of the pool, the surface accuracy of the cut surface is deteriorated. Therefore, RSm is set to 50 μm or more.

(4) Index of deviation of roughness curve in height direction (Rsk) Index of deviation of roughness curve in height direction with respect to center line (Rs)
k) is expressed by the following equation (3).

[0020]

(Equation 3)

If Rsk exceeds +1.5, it becomes difficult for cutting chips to be discharged out of the pool between the irregularities on the surface of the ID blade during cutting, thereby deteriorating the surface accuracy of the surface to be cut. Therefore, Rsk is set to +1.5 or less. More preferably, it should be a negative value.

Only when the above four parameters are controlled within the above ranges, loss due to poor cutting of the surface to be cut is small and excellent surface accuracy can be imparted to the surface to be cut. These surface properties can be formed by known means. For example, surface properties can be controlled by roll transfer using a work roll having an appropriate surface roughness at the time of finish rolling in cold rolling.

The material for the ID blade substrate is required to be high-strength stainless steel in order to secure breakage resistance and corrosion resistance when cutting a single crystal. Here, the high strength in the present invention means that a 1.0% onset stress (deformation stress when a 1.0% tensile strain is applied) is 1500 N / mm ² or more in order to secure rupture resistance. Intend. FIG.
Shows how to determine the 1.0% onset stress.

[0024] The stainless steel sheet for an ID blade substrate of the present invention does not have to limit the type of steel as long as the above strength is satisfied. Any of metastable austenitic stainless steel, metastable austenitic PH stainless steel, martensitic PH (precipitation hardening) stainless steel, and austenitic PH stainless steel may be used as the material.

However, in order to obtain this strength with a metastable austenitic stainless steel, the amount of martensite in the stainless steel must be 40 vol. % Is desirable. That is, if the amount of martensite is less than 40%, the above strength cannot be obtained. On the other hand, the amount of martensite is 9
5 vol. %, The required strength is obtained, but the ductility is too low to ensure the rupture resistance. For this reason, the amount of martensite in the plate thickness used as an ID blade is 40 to 95 vol. % Is desirable. The stainless steel targeted in the present invention substantially contains an austenite phase as a phase other than martensite, and may further contain an intermetallic compound.

In order to obtain high strength from the above metastable austenitic stainless steel, the component composition is as follows: C: 0.01
~ 0.20 wt. %, Si: 3 wt. % Or less, Mn: 3
wt. % Or less, Ni: 4 to 11 wt. %, Cr: 12-
20 wt. %, Cu: 4.5 wt. % Or less, N: 0.0
5 to 0.20 wt. %, Al: 2.0 wt. %Less than,
O: 0.020 wt. % Or less, and S as an impurity is 0.020 wt. % Is desirable.

(1) C is an austenite-forming element and contributes to suppressing the formation of the δ-ferrite phase and strengthening the solid solution of the martensite phase. %, The effect is not sufficiently obtained, while 0.20 wt. %, Cr carbide precipitates to deteriorate corrosion resistance and ductility. For this reason, C is 0.01 to 0.20 wt. % Is desirable.

(2) Si is an element that contributes to solid solution strengthening of the austenite phase and the martensite phase.
t. %, A δ-ferrite phase is formed to degrade hot workability. For this reason, 3 wt. % Is desirable. (3) Mn is an austenite phase forming element and is required for austenite single phase formation by solution treatment or deoxidation. %, The austenite phase is excessively stabilized, so that the formation of a martensite phase is extremely suppressed. Therefore, Mn is 3 wt. % Is desirable.

(4) Ni is a strong austenite phase forming element, and 4 wt. %, An austenite single phase after annealing cannot be obtained. %, The austenite phase is excessively stabilized, so that the formation of a martensite phase is extremely suppressed. Therefore, Ni is 4 to 11
wt. % Is desirable. (5) Cr is an essential element of stainless steel, and in order to obtain sufficient corrosion resistance, 12 wt. % Or more is required, but 20 wt. %, A large amount of δ-ferrite phase is formed at a high temperature, and the hot workability deteriorates. Therefore, C
r is 12 to 20 wt. % Is desirable.

(6) Cu strengthens the structure of the passive film,
It is an element that imparts the necessary corrosion resistance when used as an ID blade. %, The effect is saturated, and conversely, C which is not dissolved in the austenite phase
u increases and hot workability deteriorates. For this reason, 4.5 wt. % Is desirable. (7) N is an austenite-forming element and an element that contributes to solid solution strengthening of the martensite phase.
0.05 wt. %, This effect cannot be obtained sufficiently.
On the other hand, 0.20 wt. % Causes blowholes during casting. Therefore, N is 0.05 to
0.20 wt. % Is desirable.

(8) Al (sol. Al) is an element necessary for deoxidation. %, Al2 O
Non-metallic inclusions containing a large amount of 3 and having low extensibility are generated, which causes surface defects and increases the probability of blade breakage. Therefore, 0.020 wt. % Is desirable. (9) O is 0.020 wt. %, Al2 O3
, MnO, SiO2, Cr2 O3, and many other non-metallic inclusions are generated, deteriorating hot workability and increasing the probability of blade breakage. Therefore, O is 0.
020 wt. % Is desirable. (10) S forms nonmetallic inclusions such as MnS, and these inclusions tend to be the starting point of blade breakage. Especially,
0.020 wt. %, The ductility decreases and the fracture probability increases. For this reason, S is 0.020 wt. % Is desirable.

The high-strength stainless steel sheet described above can be manufactured by a known process. After annealing and pickling a stainless steel strip having a predetermined composition, each step of cold rolling, annealing, and low-temperature heat treatment may be performed. Further, a thin cast plate cast or a steel plate obtained by hot rolling the cast thin plate may be used. However, more preferably, it is necessary to control the following points.

(1) Atmosphere in annealing before finish rolling and in low-temperature heat treatment after finish rolling When performed in an oxidizing atmosphere, pickling treatment is required.
This pickling treatment does not provide the required surface properties due to intergranular corrosion formed on the surface of the thin plate. In addition, the above treatment was carried out at 70 vol. % In a non-oxidizing atmosphere, the surface properties required for the formation of precipitates on the surface of the thin plate cannot be obtained, and the corrosion resistance required in an environment used as an ID blade cannot be obtained. To
The required surface properties cannot be maintained during repeated use. For this reason, the annealing before the finish rolling and the low-temperature heat treatment after the finish rolling are performed at 70 vol. % Or more in a non-oxidizing atmosphere.

(2) Total Rolling Rate in Finish Rolling If the total rolling rate in finish rolling is less than 50%, the roll rolls are not sufficiently transferred, so that the surface roughness of the thin plate cannot be controlled within a predetermined range, while 76% Even if it exceeds, the transfer effect of the roll is saturated and rolling becomes difficult from the viewpoint of mill load. For this reason, the total rolling reduction in finish rolling is
It is preferable to carry out at 50 to 76%.

By using a material that satisfies the above-described conditions, a stainless steel sheet for an ID blade substrate having extremely excellent cutting properties and cutting surface precision can be obtained.

[0036]

Embodiments of the present invention will be described below. In this example, a stainless steel thin plate for an ID blade substrate was manufactured from a metastable austenitic stainless steel. First, the inventors of the present invention made steel No. 1 having a chemical composition as shown in Table 1.
No. 1 and No. 2 were melted, and after ingot casting and slab rolling, they were used as hot-rolled steel strips.

[0037]

[Table 1]

Then, the hot-rolled steel strip is annealed, pickled, subjected to intermediate annealing and intermediate cold rolling, and then sequentially subjected to final annealing, final cold rolling (finish rolling) and low-temperature heat treatment. A thin stainless steel plate for an ID blade substrate was manufactured. In addition, the total rolling reduction in the finish rolling reduction is 50-7.
6%, rolling rate per pass (total rolling rate divided by the number of passes) is 3 to 15%, annealing temperature in final annealing is 950 to 1150 ° C, and low temperature heat treatment temperature is 300 to 60.
By setting the processing time to 0 ° C. and the processing time to 1 to 300 seconds, a material that satisfies the high strength, ductility, plate thickness accuracy, and macroscopic shape (warpage, middle elongation, etc.) required for the material for the ID blade substrate is obtained. I got it.

In the above manufacturing method, as shown in Table 2, annealing (final annealing) and low-temperature heat treatment before finish rolling are performed in various atmospheres, and work rolls having various surface roughnesses are used in finish rolling. And rolled to obtain test materials Nos. 1 to 9 having surface roughness and martensite amount as shown in Table 3. Test materials Nos. 1-4 are examples of the present invention, and Nos. 5-9 are comparative examples.

[0040]

[Table 2]

[0041]

[Table 3]

Test materials Nos. 1 to 9 were used as substrates
Among the D blades, those having a good result of the pull-up test were subjected to a wafer cutting test of a Si ingot, and the quality of the manufactured wafer was evaluated based on the percentage of defective products. The reject rate is shown in Table 3 above. Test material N of the present invention example
o. All of the wafers cut with ID blades using the materials Nos. 1 to 4 had a reject rate of less than 5%. In particular, as shown in test materials No. 2 and No. 3, Ra, Rmax, RS
When m is within the specified range and Rsk is negative, the dischargeability of cutting chips to the outside of the blade surface is further improved, which is preferable, and the defective wafer rate is also low, less than 1%.

On the other hand, the ID blade using the material of the test material No. 5 of the comparative example had a small Ra and caused strong friction between the ID blade surface and the wafer surface, resulting in a large in-plane distortion applied to the wafer. Sufficient surface accuracy was not obtained, and the reject rate reached 15%.

I using the material of the test material No. 6 of the comparative example
The D-blade had a small RSm, so that the cutting chips being cut were not sufficiently discharged to the outside of the ID blade surface, so that the smoothness and flatness of the wafer were poor, and the reject rate reached 25%.

I using the material of the test material No. 7 of the comparative example
The D-blade had a large Ra and was not sufficiently discharged to the outside of the ID blade surface for cutting chips during cutting, so that the smoothness and flatness of the wafer were poor, and the reject rate reached 30%.

I using the material of the test material No. 8 of the comparative example
The D blade has a large Rmax and the ID of the cutting chips being cut.
Since the discharge to the outside of the blade surface was not sufficient, the smoothness and flatness of the wafer were poor, and the defective product ratio reached 35%.

I using the material of the test material No. 9 of the comparative example
The D-blade had a large Rsk and was not sufficiently discharged to the outside of the ID blade surface for cutting chips during cutting, so that the smoothness and flatness of the wafer were poor, and the reject rate reached 25%.

[0048]

As described above, the ID blade using the stainless steel thin plate for the ID blade substrate of the present invention exhibits extremely excellent machinability and extremely excellent surface accuracy of the surface to be cut. Therefore, it is possible to sufficiently cope with future high integration of ICs as well as cutting of current IC wafers, and the industrial effect is extremely high in that it contributes to improvement in wafer yield and cost reduction.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing how to determine a 1.0% onset stress.

────────────────────────────────────────────────── ─── Continued on the front page (72) Tadashi Inoue, 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (72) Hiroshi Tachibana 1-1-2, Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan (56) References JP-A-7-233448 (JP, A) JP-A-6-41686 (JP, A) JP-A-62-238333 (JP, A) JP-A-60-243225 (JP, A) A) (58) Field surveyed (Int. Cl. ⁶ , DB name) C21D 8 / 02,8 / 04 C21D 9 / 46,9 / 48 B21B 1/00-3/02

Claims (3)

(57) [Claims] 1. A center line average roughness (Ra) of a surface is 0.0
2 to 0.20 μm, maximum roughness (Rmax) 2.0 μm
A high-strength stainless steel sheet for an ID blade, wherein an average distance between irregularities (RSm) is 50 μm or more and an index (Rsk) of deviation in a height direction of a roughness curve is +1.5 or less. 2. The martensitic phase in the material is 40 to 95.
vol. The high-strength stainless steel sheet according to claim 1, wherein the balance is substantially an austenite phase. 3. A method for producing a high-strength stainless steel sheet according to claim 1, comprising a step of producing a steel strip, a step of performing annealing and cold rolling, and a step of performing low-temperature heat treatment. In cold rolling, annealing before finish rolling and low-temperature heat treatment after finish rolling are performed using H ₂ gas 70 vol.
l. %, Wherein the finish rolling is performed using a bright roll with a total rolling reduction of 50 to 76%.