JPH11274162A - Semiconductor substrate and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the fear of the occurrence of particles and to retain the gettering ability up to the final process, by forming machining stress layers on both faces in a grinding process, forming dislocations from the stress layers in later heat treatment, simultaneously polishing both faces and executing a mirror surface polishing process for leaving a dislocation layer only on the back face. SOLUTION: The plane grinding of a surface and a back face is executed for removing unevenness on the slice face of a semiconductor substrate 10 and a non-uniform stress layer, and uniform stress layers 11 and 12 different in depth are formed on the surface and the back face. The substrate is cleaned with a condition that the machining stress layers remain and the stress layers are cleaned. It is heat-treated with a condition that dislocations are generated from the stress layers. Then, the dislocation layers of about 5 μm is formed on the surface side and that of about 10 μm on the back face. Then, double face polishing machine polishes in mirror surface one face for about 10 μm, and the stress layer 11 of the surface, the stress layer 13 and the stress layer 12 on the back face are removed. Thus, the semiconductor substrate 10 which has the stress layer 14 on the back face and which does not have COP (initial crystal particle) on the surface can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly planarized semiconductor substrate having stable gettering ability and having no surface grown-in defects, and a method of manufacturing the same. Through the process, a gettering layer having no dust generation and a long persistence of gettering is provided on the back surface, a layer having no grown-in defects is formed on the surface layer, and a semiconductor substrate having extremely good flatness is manufactured. The present invention relates to a well-manufactured semiconductor substrate and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as a method for easily manufacturing a semiconductor substrate having a gettering ability, a method of providing mechanical processing distortion or laser thermal distortion on the back surface of a substrate, and a method of implanting an ion beam on the back surface of a substrate to provide distortion. There is an extrinsic gettering (EG) method such as a method of diffusing phosphorus on the front and back surfaces, and a method of adding HCl in an oxidizing atmosphere to oxidize hydrochloric acid on the substrate surface. In addition, there is an intrinsic gettering (IG) method using an oxygen precipitate inside a semiconductor substrate.

Japanese Patent Application Laid-Open No. 55-8067 discloses that when a mechanical strain is formed on the front and back surfaces of a substrate 1, a silicon single crystal block is first sliced into a disk shape as shown in FIG. A silicon wafer having processing strain layers 2 and 3 on its surface is obtained. The work strain layers 2 and 3 include a crack layer, a mosaic layer, a polycrystalline layer, etc., and may be a mechanically deteriorated layer. Then, both surfaces are ground to a required depth by grinding and smoothed to obtain both work strains. Process layers 2 and 3 to a uniform thickness.

Next, as shown in FIG. 3B, dislocations are generated to a required depth by an appropriate heat treatment, for example, a heat treatment at 1000 ° C. for 20 minutes to form dislocation layers 4 and 5. Further, as shown in FIG. 3C, both surfaces are processed by etching to remove the processed strained layers 2 and 3, and the dislocation layers 4 and 5 are adjusted to a required thickness.

[0007] Finally, as shown in FIG. 3 D, only the surface of the device fabrication surface is mirror-polished to completely remove the dislocation layer 4, leaving the rear surface dislocation layer 5. Therefore, no warping occurs because the processed strain layer does not remain, and gettering can be performed in the dislocation layer 5 on the back surface during device fabrication.

On the other hand, as a gettering source for a so-called epitaxial silicon semiconductor substrate in which a high-quality epitaxial layer substantially free of crystal defects is grown on the surface of a silicon wafer, B, which damages the back surface of the substrate, is used.
In addition to the method of obtaining an SD type substrate, there is a PBS type in which a polycrystalline silicon film is formed on the back side surface by etching under reduced pressure or the like after etching or mirror polishing, or a substrate doped with boron at a high concentration is used. Further, there is an IG method using an oxygen precipitate inside the silicon semiconductor substrate.

[0007]

However, in the conventional manufacturing method, an etching step and a one-side polishing step are required to leave a transition layer on one side, and the steps are complicated. Further, since the back side surface is an etched surface, there is a problem that particles are generated from the back side, and further, there is a problem that it is difficult to cope with high flatness of a semiconductor substrate accompanying high integration of devices.

[0008] Also, COP (Crystal Orig)
There is a problem that pits having a depth of about 0.1 μm, which are called integrated particles, are present on the surface, which lowers the device yield. This is a crystal defect (grown-in defect) formed during the growth of a single crystal, and it has been reported that the crystal defect is a cavity and an oxide film is formed on the inner wall.

[0009] Also, in the epitaxial silicon semiconductor substrate, there is a concern that particles may be generated on the BSD type substrate, and that the gettering ability may be reduced or eliminated by performing the device heat treatment process on both the BSD type substrate and the PBS type substrate. However, there is a problem that gettering ability cannot be expected until the final process of the device. Further, the IG method has a problem that gettering ability cannot be expected in an initial step of device fabrication.

The present invention has been made in view of the above-mentioned problems relating to the manufacture of a semiconductor substrate having gettering ability, and has no fear of generation of particles, no decrease or disappearance of gettering ability from the initial stage to the final step of the device, and An object of the present invention is to provide a semiconductor substrate with good flatness that can be manufactured at low cost without COP, can be expected to improve device yield, and a method for manufacturing the same.

[0011]

Means for Solving the Problems The inventor of the present invention has no concern about generation of particles, has no decrease or disappearance of gettering ability from the initial stage to the final process of the device, and has a grown surface on the surface.
As a result of various investigations for the purpose of semiconductor substrates with good flatness without in-defects, formed a strained layer on both sides in the grinding process, then formed dislocations from the strained layer by heat treatment, and simultaneously polished both sides, dislocations only on the backside Through a mirror polishing step that leaves a layer, a gettering layer with long dust-free gettering durability is provided on the back surface to form a layer without a grown-in defect on the surface layer, and has extremely good flatness. Semiconductor substrate,
The present inventors have found that they can be manufactured with good manufacturability, and have completed the present invention.

That is, according to the present invention, a work strain layer is formed on the front and back surfaces of a semiconductor substrate, and then dislocations are generated from the work strain layer to form a dislocation layer. To obtain a substrate having a mirror surface on the front and back surfaces and having a dislocation layer on the back surface.

Further, the present invention is a method of manufacturing a semiconductor substrate, characterized in that a heat treatment is performed in a temperature range of 1100 ° C. or higher and a melting point or lower to form a dislocation layer.

Further, according to the present invention, a processing strain layer is formed on the front and back surfaces of a semiconductor substrate, and thereafter, the temperature is 500 ° C. or more and 1000 ° C.
A heat treatment is performed in the following temperature range to generate dislocations from the strained layer to form a dislocation layer, and further, both sides are simultaneously polished to leave a dislocation layer only on the back surface, and an epitaxial silicon layer is formed on the surface. This is a method of manufacturing a semiconductor substrate.

Further, according to the present invention, in each of the manufacturing methods having the above-described structures, the processing strain layers are formed at different depths on the front and back surfaces of the semiconductor substrate, and the abrasive grain diameters acting on the front and back surfaces of the semiconductor substrate are changed. Forming a strained layer at a depth, controlling the polishing rate ratio of the front and back surfaces by simultaneous polishing on both sides, leaving a dislocation layer only on the back side, and continuously forming and forming a processed strained layer and mirror-polishing process by simultaneous processing on both sides In each case.

According to the manufacturing method of the present invention, a semiconductor substrate having an extremely flat surface having a dislocation layer on the back surface with mirror surfaces on the front and back surfaces is obtained by simultaneous polishing on both surfaces, and an epitaxial silicon layer is further formed on the surface of the semiconductor substrate. In addition, an epitaxial silicon semiconductor substrate having a stable gettering ability from the initial stage to the final process of the device can be easily manufactured.

In the semiconductor substrate according to the present invention, the dislocation layer does not disappear even after the device heat treatment step, has a gettering ability until the final step of the device, and improves the device yield, as compared with the BSD type or the PBS type. There is an advantage that it can be expected and there is no worry about generation of particles as compared with the BSD type.

Further, the semiconductor substrate according to the present invention has an IG
Compared with the conventional method, gettering action is obtained from an early stage of the device manufacturing process, and an improvement in device yield can be expected. Further, since there is no COP on the surface, an improvement in device yield can be expected.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The manufacturing method according to the present invention comprises forming strained layers having different depths on the front and back surfaces by using, for example, surface grinding by using counts having different diamond abrasive grain sizes, performing heat treatment, By removing the shallow work strain layer and dislocation layer on the surface on the device formation side with a double-sided polishing machine and removing only the deep work strain layer on the back surface and leaving the dislocation layer, the front and back surfaces are mirror-finished and the back surface A substrate having a dislocation layer on the side is obtained.
Such a process does not require an etching process, and since both surfaces are polished after highly accurate surface grinding, a semiconductor substrate having extremely excellent flatness can be obtained.

Further, a strained layer is formed at the same depth on the front and back surfaces by surface grinding, heat treatment is performed, and dislocations are formed. Then, polishing is performed by a double-side polishing machine. Can be changed so that the polishing conditions are different.The conditions can be realized by changing the rotation speed of the upper and lower platens, changing the polishing pad attached to the upper and lower platens, etc. Only the strained layer, the dislocation layer, and the strained layer on the back surface can be removed, and a semiconductor substrate having mirror surfaces on the front and back surfaces and having a dislocation layer on the back surface can be manufactured.

Hereinafter, a method of manufacturing a semiconductor substrate according to the present invention will be described in detail with reference to the drawings. In the method of manufacturing a semiconductor substrate, first, as shown in FIG. 1A, surface grinding is performed on the front and back surfaces of the semiconductor substrate 10 in order to remove unevenness and uneven strain layers on the slice surface of the semiconductor substrate 10. Uniform strain layers 11 and 12 having different depths are formed.

The above-mentioned surface grinding of the front and back surfaces can be performed using diamond fixed abrasive grains having different sizes.
Perform on No. 0. As a result, a strain layer of about 5 μm is formed on the front side and about 10 μm on the back side. At this time, the surface grinding can be performed simultaneously on the front and back surfaces or one surface at a time.

Next, as shown in FIG.
HF cleaning, SC2 cleaning, NaOH cleaning, KOH cleaning, ultrasonic cleaning, etc. are combined under such conditions that the processed strained layer remains, and after the strained layer is cleaned, dislocations are generated from the strained layer. , 500 ° C. or higher, for example, 900 ° C., 30
Heat treatment in a heat treatment furnace for a minute. As a result, 5
A dislocation layer having a thickness of about 10 μm is formed on the rear surface side.

The heat treatment is performed in an atmosphere of oxygen, nitrogen, argon, hydrogen, or the like, or a mixed atmosphere thereof. By this heat treatment, a donakiller treatment is also performed at the same time. In the silicon single crystal pulled by the CZ method, a crystal defect (grown-in defect) 15 formed at the time of growing the single crystal, that is, an oxide film is formed on the inner wall having a depth of about 0.1 μm and a hollow inside. Crystal defects, oxygen precipitate nuclei 16
However, if heat treatment is performed in a non-oxidizing atmosphere at a temperature of 1100 ° C. or more, the inner wall oxide film of the surface cavity is dissolved as shown in FIG. The silicon can be supplied, the cavity can be easily filled as compared with the case where there is no strained layer and no dislocation layer on the surface, and the surface layer 17 without crystal defects can be obtained. If the above heat treatment is performed in a nitrogen atmosphere, heat treatment can be performed at low cost.

It is conceivable that metal contamination remaining in the strained layer during the heat treatment may diffuse into the inside of the semiconductor. However, a metal which is gettered by the strained layer or the transition layer and becomes a device forming surface later has no metal. There is no problem because it does not remain. Since the cooling process is important for gettering, appropriate cooling is performed.

If an oxide film is formed on the surface during the heat treatment, such as by being charged or removed, the oxide film is removed with an HF solution so that subsequent polishing can be performed smoothly.

Next, as shown in FIG. 1C, one side is polished by about 10 μm with a double-side polishing machine, whereby the strained layer 11 and the dislocation layer 13 on the front side can be removed, and the strained layer 12 on the back side can be removed. it can. Thereby, the semiconductor substrate 1 having the dislocation layer 14 only on the back surface and having no COP on the front surface can be manufactured. Here, since a double-side polishing machine is used after high-precision surface grinding, the flatness is also excellent. Moreover, you may grind | polish every single surface as needed.

Further, a chamfering step or the like can be performed before the above-mentioned double-side polishing step or before the heat treatment step. In addition, a mirror polishing process of the end face can be added at an appropriate step before and after the double-side polishing step. Further, after the double-side polishing step, even if a CVD oxide film is formed on the back surface side, local plasma etching may be performed to further improve the flatness.

In the method of manufacturing a semiconductor substrate shown in FIG. 2, first, as shown in FIG. 2A, a table is formed to remove unevenness and uneven strain layers on a slice surface of a semiconductor substrate 20 containing high concentration of boron. The back surface is ground and the semiconductor substrate 20 is ground.
The uniform strain layers 21 and 22 having the same depth are formed on the front and back surfaces of the substrate. The surface grinding of the front and back surfaces is performed using the same diamond fixed abrasive grains. For example, by performing the front and back surfaces at 500 count, the strained layer 2 of about 10 μm is formed on the front and back surfaces.
1 and 22 are formed. This surface grinding can be performed simultaneously on the front and back surfaces or individually.

Next, as shown in FIG.
After cleaning the strained layers 21 and 22 by combining HF cleaning, SC2 cleaning, NaOH cleaning, KOH cleaning, ultrasonic cleaning, etc. under conditions such that the processed strained layer remains, heat treatment at a low temperature, for example, 800 ° C. 4 hours, the dislocation layers 23 and 24 of about 10 μm and the inside of the oxygen precipitate nuclei 26 grow on the front and back surfaces to become the grown oxygen precipitate nuclei 27 shown in the figure.

When the heat treatment is performed at a low temperature of 1000 ° C. or less for a short time, the size of the oxygen precipitation nuclei hardly changes at the lower temperature side, but at the higher temperature side, as shown in FIG.
Oxygen precipitation nuclei shrink. However, this heat treatment cannot reduce the crystal defects (grown-in defects) 25. Note that a lamp annealing device may be used for the heat treatment.

When heat treatment is performed at a low temperature of 1000 ° C. or less for a long time, oxygen precipitation nuclei grow inside the substrate as shown in b2 in FIG. 2, and an IG effect in the device process can be expected. Further, even with this heat treatment, crystal defects (grown-in defects) 25 formed during the growth of a single crystal cannot be reduced.

Thereafter, polishing is performed by a double-side polishing machine. Here, the polishing conditions are changed to change the polishing amount of the front surface and the back surface. This condition can be realized by changing the number of rotations of the upper and lower platens, changing the polishing pad attached to the upper and lower platens, and the like. The layer 22 can be removed, and a semiconductor substrate 20 having the dislocation layer 24 on the back surface and the COP 28 on the front surface is manufactured as shown in FIG. 2c.

Thereafter, hydrogen baking is performed to remove COP 28 on the surface, and then epitaxial growth is performed on the surface to form an epitaxial film 29. Further, the chamfering step or the like can be performed before the double-side polishing step or the heat treatment step. In addition, a mirror polishing process of the end face can be added at an appropriate step before and after the double-side polishing step. Further, after the double-side polishing step, C
Even if a VD oxide film is formed, local plasma etching may be performed to further improve the flatness.

[0035]

The semiconductor substrate according to the present invention includes a mirror polishing step in which a strained layer is formed on both sides in a grinding step, dislocations are formed from the strained layer by heat treatment, and both sides are simultaneously polished to leave a dislocation layer only on the back side. Through this process, a gettering layer can be provided without the need for an etching step, and since the front and back surfaces have a mirror surface and a dislocation layer on the back surface side, there is no need to worry about particle generation, and the gettering process can be performed from the initial stage to the final process of the device. There is no decrease or disappearance of the ring ability, no COP on the surface, and a semiconductor substrate with extremely good flatness by simultaneous double-side polishing can be manufactured with good manufacturability.

[Brief description of the drawings]

FIGS. 1A to 1C are cross-sectional views of a semiconductor substrate showing a flow of manufacturing a semiconductor substrate according to the present invention.

FIGS. 2A to 2D are cross-sectional views of a semiconductor substrate showing a flow of manufacturing another semiconductor substrate according to the present invention.

FIGS. 3A to 3D are cross-sectional explanatory views of a semiconductor substrate showing a flow of fabricating the semiconductor substrate by a conventional manufacturing method.

[Explanation of symbols]

 1,10,20 Semiconductor substrate 2,3 Work strain layer 4,5,13,14,23,24 Dislocation layer 11,12,21,22 Strain layer 15,25 Crystal defect 16,26,27 Oxygen precipitation nucleus 17 Crystal Defect-free surface layer 28 COP 29 epitaxial film

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[Procedure amendment]

[Submission date] October 16, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction contents]

[0007]

[SUMMARY OF THE INVENTION However, in the conventional manufacturing method requires an etching step and single side polishing step in order to leave dislocation layer on one side, the process is complicated. Further, since the back side surface is an etched surface, there is a problem that particles are generated from the back side, and further, there is a problem that it is difficult to cope with high flatness of a semiconductor substrate accompanying high integration of devices.

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Figure 2

[Correction method] Change

[Correction contents]

FIG. 2

Claims (9)

[Claims] 1. A semiconductor substrate having a dislocation layer on the back surface and mirror surfaces on the front and back surfaces. 2. The method according to claim 1, wherein a surface of the ground-
A semiconductor substrate having a layer free of in-defects. 3. A distorted layer is formed on the front and back surfaces of the semiconductor substrate, dislocations are generated from the distorted layer to form dislocation layers, and both sides are simultaneously polished to leave dislocation layers only on the back surface. And a method of manufacturing a semiconductor substrate for obtaining a substrate having a mirror surface on both sides and a dislocation layer on the back surface. 4. The method for manufacturing a semiconductor substrate according to claim 3, wherein a heat treatment is performed in a temperature range of 1100 ° C. or more and a melting point or less to form a dislocation layer. 5. A distorted layer is formed on the front and back surfaces of the semiconductor substrate, and then heat treatment is performed at a temperature in the range of 500 ° C. to 1,000 ° C. to generate dislocations from the distorted layer to form dislocation layers. A method of manufacturing a semiconductor substrate in which a dislocation layer is left only on a back surface by performing simultaneous polishing and an epitaxial silicon layer is formed on a front surface. 6. The method of manufacturing a semiconductor substrate according to claim 3, wherein a strained layer is formed at different depths on the front and back surfaces of the semiconductor substrate. 7. The method of manufacturing a semiconductor substrate according to claim 6, wherein the processing strain layers are formed at different depths by changing the abrasive grain diameter acting on the front and back surfaces of the semiconductor substrate. 8. The method of manufacturing a semiconductor substrate according to claim 3, wherein a polishing rate ratio of the front and back surfaces is controlled by simultaneous polishing of both surfaces to leave a dislocation layer only on the back surface. 9. The method of manufacturing a semiconductor substrate according to claim 3, wherein the step of forming a work strain layer and the step of mirror polishing are continuously performed by simultaneous double-sided processing.