JPS63166237A - Method of processing semiconductor substrate - Google Patents

Abstract

PURPOSE:To simplify an intrinsic gettering process and reduce its time, by a method wherein a non-defective layer is formed on the surface layer part of a substrate by performing, in a non-oxidizing atmosphere and at a specified temperature, heat treatment of a semiconductor substrate whose surface is subjected to lapping, heat treatment is performed to form a defective layer in the inside, and then polishing of the non- deflective layer in the substrate is performed up to a necessary depth. CONSTITUTION:A sliced semiconductor substrate, for example, a silicon substrate 1 is subjected to a mechanical lapping up to a depth necessary to eliminate damages due to slicing. In a heating process, a silicon substrate 3 subjected to this lapping is heated at a temperature higher than or equal to 1000 C for a specified time in a non-oxidizing gas, such as nitrogen (N2) or rare gas. Thus, I-Si existing in a substrate surface layer is diffused, and a non-defective layer is formed in the substrate surface layer. Further, I-Si existing in the inside is collected, and a defective layer is formed. After a heat treatment 4, the substrate is abraded up to a necessary width for a non- defective layer, and subjected to polishing to form a mirror type substrate 6. Thereby, the forming process of a substrate with intrinsic gettering effects can be remarkably simplified and its necessary time can be reduced.

Description

[Detailed Description of the Invention] [Summary] After lapping the semiconductor substrate, the semiconductor substrate is
The interstitial atoms present in the surface layer are heated to a temperature of 0°C or higher to diffuse out to form a defect-free layer in the surface layer, and the interstitial atoms present in the internal layer are aggregated to form the inner layer. Stacking faults are generated in the semiconductor substrate, and the defect-free layer is then polished to a thickness such that the distance between the bottom surface of the semiconductor element formed in the defect-free layer and the internal defect precipitation layer is a required distance. With this processing method, the process of forming a semiconductor substrate structure, which has the effect of trapping contaminant impurities in the semiconductor element formation region into internal stacking faults and improving semiconductor element performance, is simplified and significantly shorter than conventional methods. Ru.

[Industrial application field]

The present invention relates to a method of processing a semiconductor substrate, and more particularly to a method of processing a semiconductor substrate for forming an intrinsic gettering structure.

Silicon single crystals used in the manufacture of semiconductor devices are generally manufactured by the Czochralski (CZ) method, but since a crucible usually made of quartz glass is used, the silicon single crystals finally obtained are 30~ in the crystal
Oxygen atoms are included at a high concentration of about 40 ppm. Therefore, when manufacturing semiconductor devices such as ICs using a silicon substrate formed from the silicon single crystal, there are Oxygen atoms contained in the semiconductor grow into crystal defects within the substrate, and further combine with contaminant impurities such as heavy metals, resulting in a problem that the performance of the semiconductor device is degraded.

Therefore, there is a need for a method for processing semiconductor substrates to avoid contamination by heavy metals and the like during the above-mentioned high-temperature manufacturing process.

[Conventional technology]

A substrate heat treatment method called the intrinsic gettering (IG) method has been widely used in the past to avoid contamination by heavy metal impurities and the like.

The operating region of semiconductor devices such as ICs is usually formed in the surface layer about 10 μm or less from the surface of the silicon substrate, so in order to avoid performance deterioration due to the above-mentioned contaminating impurities, at least only the surface layer should be made defect-free. In addition, it may be formed as a layer that does not contain contaminating impurities.

Therefore, in the conventional IC method described above, the silicon substrate is first heated at 110 nm in a non-oxidizing atmosphere.
A first heat treatment is performed at 0°C for about 1 hour to make the surface layer of the semiconductor substrate defect-free by diffusing oxygen atoms in the surface layer, and then heat treatment is performed at a temperature of about 600°C for 200 minutes.
After performing a second heat treatment for about an hour to precipitate the oxygen atoms inside the substrate as defect nuclei, a third heat treatment for about an hour is performed at a temperature of about 800 to 1000°C to turn the defect nuclei into crystal defects. By growing, a defective layer having many crystal defects is formed inside the semiconductor substrate.

Then, due to the gettering effect of the crystal defects on the contaminant impurities, the contaminant impurities in the defect-free layer in the surface layer of the substrate are removed to the inside of the substrate, and due to the impurity contamination of the operating region formed in the surface layer of the substrate. Performance deterioration is prevented.

FIG. 4 schematically shows a cross section of a silicon substrate 51 subjected to the above-mentioned IG treatment. In the figure, 52 is a defect-free layer formed on the surface layer of the substrate by oxygen atoms diffused out, and 53 is an oxygen atom. 54 represents a defect layer inside the substrate in which a large number of crystal defects due to oxygen atoms are present.

The conventional IC method using the method described above has a sufficient effect of avoiding contamination by heavy metals in the active region formed on the surface layer of the substrate. However, as shown in the above representative example, there was a problem that the heat treatment process was complicated and required an extremely long time.

[Problem that the invention seeks to solve]

The problem to be solved by the present invention is that the conventional IC method used to avoid heavy metal contamination in the manufacturing process of semiconductor devices is complicated and takes a long time.

[Means for solving problems]

The above problem lies in the processing method for semiconductor substrates used in the manufacture of semiconductor devices.
), and the lapped semiconductor substrate (3) is heat-treated at a temperature of 1000°C or higher in a non-oxidizing atmosphere to form a defect-free layer on the surface layer of the semiconductor substrate. At the same time, a heat treatment step (4) for forming a defective layer inside, and a step (5) for polishing the defect-free layer of the semiconductor substrate after the heat treatment to a required thickness.
) is solved by a method for processing a semiconductor substrate according to the present invention.

[For production]

That is, in the method of the present invention, a semiconductor substrate, such as a silicon substrate, is heat-treated at a temperature of 1000° C. or higher, such as 1100° C., for about 0.5 hours in a non-oxidizing atmosphere, thereby removing interstitials in the substrate crystal.
Since the diffusion constant of the 1-3i atoms at 1100°C is approximately 10-' [cm/sec], based on the following formula, ( 10-'x60"Xo, 5) #130 [μm
Move it about l.

As a result of this movement, a layer with a width of about 130 μm is formed from the surface.
The -5i atoms are diffused out to make the region defect-free, and the l-5t atoms in the inner layer are aggregated by the above movement to precipitate stacking faults in the inner layer.

Next, when a semiconductor element is formed on the surface of the defect-free layer of the silicon substrate that has been heat-treated as described above, that is, the surface of the defect-free layer, contaminating impurities due to crystal defects in the defect layer inside the substrate are removed. The defect-free layer is mirror-polished by a polishing method to a required defect-free layer width of, for example, 50 to 60 μm so that the gettering effect extends to the surface of the defect-free layer.

As described above, a semiconductor substrate having the same intrinsic gettering effect as the conventional one can be easily formed through processing steps that are simplified and significantly shortened compared to the conventional one.

〔Example〕

The present invention will be specifically explained below with reference to illustrated embodiments.

Figure 1 is a schematic diagram showing the principle of the present invention, Figure 2 is a schematic diagram of the first embodiment of the present invention, and Figures 3 (a) to ('b) are schematic cross-sectional views of the polishing process. be.

The principle of the semiconductor substrate processing method according to the present invention is as shown in the process diagram schematically shown in FIG. Rough ping step 2 involves polishing and removing the silicon substrate 3, and nitrogen (N2
) or 1000℃ in non-oxidizing gas such as rare gas
When heated at a temperature above for a predetermined period of time, the l
-3i is diffused to form a defect-free layer on the surface layer of the substrate, and l-5i existing inside is aggregated to form a defective layer; a heat treatment step 4 of silicon after the heat treatment step 4; The present invention is characterized in that it includes a polishing step 5 in which the substrate is polished to a desired defect-free layer width by ordinary mechanical/chemical polishing means and finished into a mirror-like silicon substrate 6. Incidentally, the mirror-like semiconductor substrate 5 that has undergone the processing according to the present invention is then introduced into a process step 7 for semiconductor devices such as ICs.

When applied to an actual process, for example, as in the embodiment shown in FIG. Semiconductor substrate 3 polished and lapped to the extent that slice damage is removed
form.

Next, a normal organic solvent cleaning 8 using trichloride, alcohol, acetone, etc. is performed to remove the oil and fat bones on the substrate surface, and then the substrate surface is washed with fluoronitric acid as usual until the damage from lapping is removed and the surface is almost flat. After etching treatment 9 with a solution of 1 and then cleaning 10 for removing metal components such as heavy metals with aqueous ammonia or the like as usual, the wrapped substrate 3 is sent to a heat treatment step 4.

In the heat treatment step 4, a non-oxidizing gas such as N
Heat treatment is performed at 1100° C. for about 30 minutes during t. As a result of this heat treatment, the 1-Si in the surface layer of the substrate 3 is diffused out and lost as described above, and a defect-free layer having a depth, that is, a width of about 130 .mu.m, is formed in the surface layer. At the same time, the l-5i inside the substrate aggregate to generate stacking faults as described above, and a defective layer with many stacking faults is formed in the internal region of the substrate.

Next, the heat-treated silicon substrate surface is sent to a normal polishing step 5 for mirror-finishing the surface, and the silicon substrate surface is polished to eliminate stacking defects existing in the internal defect layer in the semiconductor element formation region of the surface portion of the defect-free layer. The thickness at which the trapping effect of contaminant impurities is achieved, that is, the layer width, for example, 50 to 60 μm
It is chemically polished and finished to a mirror surface using normal mechanical/chemical polishing methods.

After the polishing, the silicon substrate 6 is sent to a manufacturing process 7 for semiconductor devices such as ICs through normal cleaning and drying steps (not shown).

FIG. 3 is a schematic cross-sectional view schematically showing the polishing process described above, and as shown in (al) of this figure, the defect-free N11 formed with a width 6 of about 130 μm by the heat treatment process 4 is An internal defect precipitation layer 1 is formed in the operating region of the semiconductor element, which is formed on the surface to a depth of about 10 μm or less.
As described above, polishing is performed to a width of about 50 to 60 μm so that the gettering effect of contaminant impurities caused by the stacking faults 13 existing in 2 is applied.

As shown in the embodiments above, according to the method of the present invention, a layered layer having a defect-free layer on the surface layer of the silicon substrate on which the operating region of a semiconductor device is formed, and trapping contaminant impurities such as heavy metals inside. It has a defect layer in which many defects are formed,
A silicon substrate having the same IC effect of contaminant impurities as in the past can be formed by a heat treatment process that is simpler and much shorter than the conventional one.

Note that the polishing in the present invention is not double-sided polishing as shown in the drawings, but may be single-sided polishing only on the main surface side.

〔Effect of the invention〕

As explained above, according to the method of the present invention, the surface layer has a defect-free layer and the interior has a defect layer, which is effective for improving and stabilizing the performance of semiconductor devices such as ICs. The process of forming a semiconductor substrate having an intrinsic gettering effect of impurities can be greatly simplified and made simpler.

[Brief explanation of the drawing]

Fig. 1 is a schematic 1st step diagram showing the principle of the present invention, Fig. 2 is a schematic 1st step diagram of an embodiment of the present invention, Fig. 3 is a schematic cross-sectional view of the polysocing process, and Fig. 4 is a conventional IG process. FIG. 2 is a schematic cross-sectional view of a silicon substrate subjected to a process. In the figure, step is a silicon substrate after slicing, 2 is a wrapped silicon substrate, 3 is a wrapped silicon substrate, 4 is a heat treatment process, 5 is a polysocing process, 6 is a mirror finished silicon substrate, 7 is a RC manufacturing process, 8 is an organic 9 is an etching process, 10 is a metal impurity cleaning process, 11 is a defect-free layer, 12 is a stacking fault layer, and 13 is a stacking fault. Toru 1 @ Tea 2 Figure

Claims (1)

[Claims] A method for processing a semiconductor substrate used in manufacturing a semiconductor device, comprising: a step (2) of lapping the surface of a sliced semiconductor substrate (1); and a step (2) of lapping the surface of a sliced semiconductor substrate (3). a heat treatment step (4) of forming a defect-free layer on the surface layer of the semiconductor substrate and forming a defect precipitation layer inside by heat-treating the semiconductor substrate at a temperature of 1000° C. or higher in a non-oxidizing atmosphere; A method for processing a semiconductor substrate, comprising a step (5) of polishing the defect-free layer of the finished semiconductor substrate to a required thickness.