TWI653668B - Manufacturing method of semiconductor device - Google Patents

Abstract

The method for manufacturing a semiconductor device of the present invention includes a dissolving step to prepare an aqueous solution after dissolving aluminum lactate in water; a mixing step to produce a mixed solution obtained by mixing an aqueous solution and an organic solvent; and manufacturing a semiconductor dopant liquid containing the mixed solution. A coating step, after the mixing step, a semiconductor dopant liquid source containing an aqueous solution is coated on the semiconductor substrate to form a diffusion source cover film on the semiconductor substrate; the firing step, after the coating step is performed, The semiconductor substrate is heated at a first temperature in an atmosphere to fire at least an organic solvent in the diffusion source cover film; and in a diffusion step, after the firing step is performed, the semiconductor substrate is fired in a second atmosphere. The heat treatment is performed at a second temperature higher than the first temperature to diffuse aluminum contained in the diffusion source cover film on the semiconductor substrate, thereby forming a diffusion layer on the semiconductor substrate.

Description

Manufacturing method of semiconductor device

The present invention relates to a method for manufacturing a semiconductor device.

Conventionally, there is a method of manufacturing a conductor device in which a diffusion source cover film containing an aluminum compound and a boron compound is formed on a semiconductor substrate as a P-type dopant, and the semiconductor substrate on which the diffusion source cover film is formed is heated. Thereby, a P-type diffusion layer is formed on the semiconductor substrate (see Japanese Patent Application Laid-Open No. 2000-286205).

In particular, in order to obtain a P-type low-concentration and deep diffusion layer, it is necessary to use aluminum having a large diffusion coefficient.

Examples of the manufacturing method of the above-mentioned conventional semiconductor device include a method of dissolving an aluminum compound and a boron compound in a solvent and coating the compound on a wafer surface, or passing boron and aluminum powder through an organic binder. A method for attaching a thin film and a silicon wafer to diffusion.

However, since these conventional methods for manufacturing semiconductor devices diffuse aluminum and boron simultaneously in a non-oxidizing atmosphere limited to nitrogen or the like, it is difficult to diffuse aluminum alone.

In addition, since the aluminum compound contains components such as aluminum chloride, aluminum ethoxide, and aluminum stearate, aluminum does not diffuse on the semiconductor substrate alone.

That is, the conventional method of manufacturing a semiconductor device has the following problems: that is, the medium type is limited in the atmosphere in the diffusion step, and controllability of aluminum diffusion to the semiconductor substrate is reduced.

Therefore, in view of the above problems, the present invention aims to provide a method for manufacturing a semiconductor device, which can widen the selection range of the dielectric type in the atmosphere in the diffusion step and improve the controllability of aluminum diffusion to the semiconductor substrate.

A method for manufacturing a semiconductor device according to an aspect of the present invention includes a dissolution step of dissolving aluminum lactate in water to prepare an aqueous solution, and a mixing step of manufacturing a mixed solution in which the aqueous solution and an organic solvent are mixed, and manufacturing A semiconductor dopant liquid source containing the mixed solution; a coating step, after performing the mixing step, coating the semiconductor dopant liquid source containing the aqueous solution on a semiconductor substrate, so that the semiconductor substrate is A diffusion source cover film is formed thereon; in the firing step, after the coating step is performed, the semiconductor substrate is heat-treated at a first temperature in a first atmosphere, so that at least all of the diffusion source cover films are Firing the organic solvent; and a diffusion step, after performing the firing step, in a second atmosphere, heat-treating the semiconductor substrate at a second temperature higher than the first temperature, so that the semiconductor substrate The aluminum contained in the diffusion source cover film diffuses on the semiconductor substrate, thereby forming a diffusion layer on the semiconductor substrate.

In the method for manufacturing a semiconductor device, the organic solvent has a characteristic that the aluminum lactate is not dissolved.

In the method for manufacturing a semiconductor device, the organic solvent is any one of ethanol (Ethanol), acetone, propanol, or alcohol (Ethyl alcohol).

In the method for manufacturing a semiconductor device, the first atmosphere in the firing step is an oxidizing atmosphere.

In the method for manufacturing a semiconductor device, the second atmosphere in the diffusion step is the oxidation atmosphere.

In the method for manufacturing a semiconductor device, the oxidizing atmosphere is an oxygen-containing atmosphere.

In the method for manufacturing a semiconductor device, the coating step coats the semiconductor dopant liquid source on a semiconductor substrate by a spin coating method.

In the method for manufacturing a semiconductor device, the first temperature in the firing step is in a range of 400 ° C to 600 ° C.

In the method for manufacturing a semiconductor device, the second temperature in the diffusion step is in a range of 1000 ° C to 1300 ° C.

In the method for manufacturing a semiconductor device, the semiconductor substrate is an N-type silicon wafer.

The method for manufacturing a semiconductor device further includes a peeling step, and after performing the diffusion step, peeling a film remaining on the semiconductor substrate with a peeling liquid.

In the method for manufacturing a semiconductor device, the peeling liquid is fluoric acid.

In the method of manufacturing a semiconductor device, the semiconductor dopant liquid source further includes a thickener that dissolves in the organic solvent and imparts viscosity to the semiconductor dopant liquid source, and a plurality of inorganic powders. In the firing step, in a state in which two of the semiconductor substrates face each other so that the diffusion source cover films of the two semiconductor substrates are in contact, in the first atmosphere, The two semiconductor substrates are heat-treated at the first temperature, and in the diffusion step, the two semiconductor substrates are heat-treated at the second temperature in the second atmosphere. The inorganic powder includes: when the two semiconductor substrates are laminated, the tackifier is used to adjust the interval between adjacent inorganic powders in the plane direction of the semiconductor substrate to adjust The distribution characteristics of the interval between the two semiconductor substrates in the plane direction, and the inorganic powder further has the following characteristics: when the dopant is heated to a temperature higher than the first temperature, the dopant diffusion is generated. After the temperature of the second supply source, so as to engage said heated by the second temperature in the two When the semiconductor substrate is placed in the peeling liquid, a characteristic of impregnating the peeling liquid between the two semiconductor substrates is maintained by maintaining a gap between the two semiconductor substrates. In the peeling step, the two semiconductor substrates facing each other are separated.

In the method for manufacturing a semiconductor device, the main component of the thickener contains cellulose, a fiber bundle derivative, or hydroxypropyl cellulose.

In the method for manufacturing a semiconductor device, pre-baking is performed between the coating step and the firing step, and the semiconductor substrate is subjected to a third temperature lower than the first temperature. The heat treatment causes at least the organic solvent and the water in the diffusion source cover film to evaporate.

A method for manufacturing a semiconductor device according to an aspect of the present invention includes: a dissolving step of dissolving aluminum lactate in water to prepare an aqueous solution; a mixing step of manufacturing a mixed solution of an aqueous solution and an organic solvent; and manufacturing a semiconductor containing the mixed solution. Dopant liquid source; coating step; after the mixing step, a semiconductor dopant liquid source containing an aqueous solution is coated on a semiconductor substrate to form a diffusion source cover film on the semiconductor substrate; a firing step, and a coating step is performed Then, the semiconductor substrate is heated at a first temperature in a first atmosphere to fire at least an organic solvent in the diffusion source cover film; and a diffusion step is performed in a second atmosphere after the firing step is performed. Heating the semiconductor substrate at a second temperature higher than the first temperature to diffuse aluminum contained in the diffusion source cover film on the semiconductor substrate, thereby forming a diffusion layer on the semiconductor substrate.

In addition, in the diffusion step, aluminum in aluminum lactate, which is an aluminum compound, has a characteristic of diffusing alone on a semiconductor substrate.

In addition, although this aluminum lactate is insoluble in an organic solvent (ethanol), a semiconductor dopant liquid source containing a mixed solution with an organic solvent (ethanol) can be formed by mixing with water in advance.

In this way, according to the method for manufacturing a semiconductor device of the present invention, in the diffusion step, by using aluminum lactate as an aluminum compound to form a diffusion source cover film, it is possible to use a non-oxidizing atmosphere (oxidizing atmosphere). Aluminum diffuses separately.

That is, according to the method for manufacturing a semiconductor device of the present invention, it is possible to widen the selection range of the medium type in the atmosphere in the diffusion step, and to improve the controllability of aluminum diffusion to the semiconductor substrate.

1-N‧‧‧N-type semiconductor dopant liquid source

1-P‧‧‧P-type semiconductor dopant liquid source

11-N‧‧‧N-type dopants

11-P‧‧‧P-type dopants

12‧‧‧organic solvents

13‧‧‧Tackifier

14‧‧‧ inorganic powder

2. X‧‧‧ semiconductor substrate

2a‧‧‧ coated surface

5‧‧‧ baking plate

A‧‧‧water solution

S‧‧‧ Diffusion source cover film

Sa‧‧‧ Diffusion source cover film

Y‧‧‧ diffusion layer

Z‧‧‧Semiconductor Dopant Liquid Source

FIG. 1 is a diagram showing a configuration example of a semiconductor dopant liquid source in a method of manufacturing a semiconductor device according to the present invention.

FIG. 2 is a step display diagram of the method for manufacturing a semiconductor device according to the first embodiment.

FIG. 3 is a diagram showing steps of the method for manufacturing a semiconductor device according to the first embodiment following FIG. 2.

FIG. 4 is a diagram showing steps of the method for manufacturing a semiconductor device according to the first embodiment following FIG. 2;

FIG. 5 is a diagram showing steps of the method for manufacturing a semiconductor device according to the first embodiment following FIG. 2;

FIG. 6 is a flowchart of a method for manufacturing a semiconductor dopant liquid source according to the second embodiment.

FIG. 7 is an explanatory diagram for explaining a method for manufacturing a P-type semiconductor dopant liquid source in the method for manufacturing a semiconductor dopant liquid source according to the second embodiment.

FIG. 8 is an explanatory diagram for describing a method for manufacturing an N-type semiconductor dopant liquid source in a method for manufacturing a semiconductor dopant liquid source according to the second embodiment.

FIG. 9 is a flowchart of a method of manufacturing a semiconductor device according to the second embodiment.

FIG. 10 is a schematic cross-sectional view showing a dropping step in a method of manufacturing a semiconductor device according to a second embodiment.

FIG. 11 is a schematic cross-sectional view showing a coating step in the method of manufacturing a semiconductor device according to the second embodiment, following FIG. 10.

FIG. 12 is a schematic cross-sectional view showing a drying step in the method of manufacturing a semiconductor device according to the second embodiment, following FIG. 11.

FIG. 13 is a schematic cross-sectional view showing a lamination step in the method of manufacturing a semiconductor device according to the second embodiment, following FIG. 12.

FIG. 14 is a schematic cross-sectional view showing a firing step in the method of manufacturing a semiconductor device according to the second embodiment, following FIG. 13.

FIG. 15 is a graph showing a temperature change in a diffusion process in the method for manufacturing a semiconductor device according to the second embodiment.

FIG. 16 is a schematic cross-sectional view showing a deposition step in the method of manufacturing a semiconductor device according to the second embodiment, following FIG. 14.

FIG. 17 is a schematic cross-sectional view showing a diffusion step following FIG. 16 in the method of manufacturing a semiconductor device according to the second embodiment.

FIG. 18 is a schematic cross-sectional view showing a dipping step subsequent to FIG. 17 in the method for manufacturing a semiconductor device according to the second embodiment.

FIG. 19 is a flowchart of a method for manufacturing a semiconductor dopant liquid source according to a modification.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Example 1]

FIG. 1 is a diagram showing a configuration example of a semiconductor dopant liquid source in a method of manufacturing a semiconductor device according to the present invention. FIGS. 2 to 5 are diagrams showing steps of a method for manufacturing a semiconductor device according to the first embodiment.

As shown in FIGS. 2 to 5, the method for manufacturing a semiconductor device according to the first embodiment is performed according to the “dissolution step”, “mixing step”, “coating step”, “firing step”, “diffusion step”, and “ The steps of "peeling step" are performed sequentially. Hereinafter, a method for manufacturing a semiconductor device according to the first embodiment will be described in the order of the above steps.

Dissolution step

First, aluminum lactate was dissolved in water to prepare an aqueous solution A (Fig. 1).

Here, as the P-type semiconductor dopant liquid source for diffusing the P-type dopant on the semiconductor substrate X, aluminum lactate can be used as the dopant-containing compound.

The ratio of aluminum lactate to water in the aqueous solution A is set to, for example, about: aluminum lactate: water = 8: 100.

Mixing step

Next, a mixed solution in which the aqueous solution A and the organic solvent are mixed is prepared, and a semiconductor dopant liquid source Z containing the mixed solution is prepared (FIG. 1, a mixing step).

The organic solvent has been described so that it does not dissolve at least aluminum lactate.

Specifically, the organic solvent is, for example, any one of ethanol, acetone, propanol, or alcohol.

In this way, in this mixing step, a mixed solution in which an aqueous solution and an organic solvent are mixed is prepared, and a semiconductor dopant liquid source Z containing the mixed solution is prepared.

Coating step

Next, after performing the above-mentioned mixing step, in this coating step, a semiconductor dopant liquid source Z containing an aqueous solution A is coated on the semiconductor substrate X, thereby forming a diffusion source cover film S on the semiconductor substrate X (FIG. 2) , Coating step).

In this coating step, a semiconductor dopant liquid source is coated on the semiconductor substrate X by a spin coating method.

The semiconductor substrate X is, for example, an N-type silicon wafer.

Firing step

Next, after the coating step is performed, the semiconductor substrate X is heat-treated at a first temperature in a first atmosphere, thereby firing at least an organic solvent in the diffusion source cover film Sa (FIG. 3, firing step). .

The first atmosphere described in this firing step is an oxygen-containing atmosphere.

The first temperature in the firing step is, for example, in a range of 400 ° C to 600 ° C.

In addition, if necessary, pre-baking may be performed between the coating step and the firing step described above, and the semiconductor substrate X may be heat-treated at a third temperature lower than the first temperature, so that the diffusion source cover film Sa The evaporation of at least organic solvents as well as water. This is particularly effective when the organic solvent is a solvent other than ethanol.

Diffusion step

Next, after the firing step is performed, the semiconductor substrate X is heated at a second temperature higher than the first temperature in a second atmosphere to diffuse aluminum contained in the diffusion source cover film Sa on the semiconductor substrate X. Thus, a diffusion layer Y is formed on the semiconductor substrate X (FIG. 4, a diffusion step).

The second atmosphere described in this diffusion step is an oxygen-containing atmosphere.

The aforementioned second temperature in the diffusion step is, for example, in a range of 1000 ° C to 1300 ° C.

Stripping step

Next, after the diffusion step is performed, the film Sb remaining on the semiconductor substrate X is peeled by a peeling liquid (FIG. 5, peeling step).

The aforementioned peeling liquid is, for example, hydrofluoric acid.

Example where multiple semiconductor substrates are stacked and processed simultaneously

In the method for manufacturing a semiconductor device according to the first embodiment, for example, a plurality of (two or more) semiconductor substrates X may be stacked and processed simultaneously.

In this case, the semiconductor dopant liquid source Z is further made to contain a thickener which dissolves in an organic solvent and imparts viscosity to the semiconductor dopant liquid source Z, and various inorganic powders (for example, powders containing Si). The main component of the thickener contains cellulose, a fiber bundle derivative, or hydroxypropyl cellulose.

In the firing step described above, in a state where the two semiconductor substrates X face each other and the diffusion source cover films of the two semiconductor substrates X are in contact, the two semiconductors are exposed to the first atmosphere (for example, an oxidizing atmosphere). The substrate X is heat-treated at a first temperature (for example, 400 ° C to 600 ° C).

Further, in the diffusion step described above, the two semiconductor substrates X are heat-treated at a second temperature (for example, 1000 ° C. to 1300 ° C.) in a second atmosphere (for example, an oxidizing atmosphere).

This inorganic powder has the following advantages: when two semiconductor substrates X are stacked, the distance between the inorganic powders adjacent to each other in the surface direction of the semiconductor substrate X is adjusted by the above-mentioned thickener to adjust the two semiconductor-based X plates. The characteristics of the distribution in the plane direction of the interval.

In addition, the inorganic powder further includes two semiconductor substrates which are bonded by heating the dopant to a second temperature higher than the first temperature to generate a dopant diffusion supply source and then heating the second temperature. When X is placed in the above-mentioned peeling liquid, the characteristic of impregnating the peeling liquid between the two semiconductor substrates X is maintained by maintaining the interval between the two semiconductor substrates X.

In the aforementioned peeling step, the two semiconductor substrates X facing each other are separated.

Through the above steps, a semiconductor device after aluminum diffusion can be manufactured in a state with good controllability.

As described above, in the diffusion step, aluminum in aluminum lactate, which is an aluminum compound, has a characteristic of diffusing on the semiconductor substrate X alone.

In addition, although this aluminum lactate is insoluble in an organic solvent (ethanol), a semiconductor dopant liquid source Z containing a mixed solution with an organic solvent (ethanol) can be formed by mixing with water in advance.

As described above, in the diffusion step described above, by using aluminum lactate as the aluminum compound to form the diffusion source cover film Sa, aluminum can be individually diffused in an atmosphere (oxidizing atmosphere) that is not limited to a non-oxidizing atmosphere.

That is, it is possible to widen the selection range of the medium type in the atmosphere in the diffusion step, and to improve the controllability of aluminum diffusion to the semiconductor substrate X.

In summary, the method for manufacturing a semiconductor device according to the first embodiment of the present invention includes: a dissolving step in which aluminum lactate is dissolved in water to prepare aqueous solution A; a mixing step in which a mixed solution in which an aqueous solution and an organic solvent are mixed, and Manufacturing a semiconductor dopant liquid source Z containing a mixed liquid; a coating step, and after performing the mixing step, a semiconductor dopant liquid source Z containing an aqueous solution is coated on a semiconductor substrate to form a diffusion source cover film on the semiconductor substrate X S; a firing step, after performing the coating step, heating the semiconductor substrate X at a first temperature in a first atmosphere, thereby firing at least an organic solvent in the diffusion source cover film Sa; and a diffusion step, After the firing step is performed, the semiconductor substrate X is heated at a second temperature higher than the first temperature in a second atmosphere, so that aluminum contained in the diffusion source cover film is diffused on the semiconductor substrate X, and the semiconductor A diffusion layer Y is formed on the substrate.

In addition, in the diffusion step, aluminum in aluminum lactate, which is an aluminum compound, has a characteristic of diffusing alone on a semiconductor substrate.

Although this aluminum lactate is insoluble in an organic solvent (ethanol), by mixing with water in advance, a semiconductor dopant liquid source Z containing a mixed solution with an organic solvent (ethanol) can be formed.

In this way, according to the method for manufacturing a semiconductor device of the present invention, in the diffusion step, by using aluminum lactate as an aluminum compound to form a diffusion source cover film, it is possible to use a non-oxidizing atmosphere (oxidizing atmosphere). Aluminum diffuses separately.

That is, according to the method for manufacturing a semiconductor device of the present invention, it is possible to widen the selection range of the medium type in the atmosphere in the diffusion step, and to improve the controllability of aluminum diffusion to the semiconductor substrate.

[Example 2]

In the embodiment described above, a mode in which aluminum, which is a P-type dopant, is diffused on one semiconductor substrate has been described. However, as described above, by stacking the semiconductor substrates, aluminum, which is a p-type dopant, can be diffused on a plurality of (two or more) semiconductor substrates.

In the second embodiment, a mode in which a desired dopant is diffused on a plurality of semiconductor substrates by laminating semiconductor substrates will be described in detail. In the second embodiment, the diffusion step in the first embodiment is described as a deposition step and a diffusion step.

(Semiconductor Dopant Liquid Source)

First, a semiconductor dopant liquid source according to the second embodiment will be described.

The semiconductor dopant liquid source according to the second embodiment is heated in a state where the semiconductor dopant liquid source is applied between a plurality of stacked semiconductor substrates to diffuse the dopants on the plurality of semiconductor substrates. In this manner, by diffusing the dopant on a plurality of semiconductor substrates in a stacked state, the dopant can be diffused simultaneously on the plurality of semiconductor substrates, so that the dopant diffusion can be efficiently performed. .

The semiconductor dopant liquid source contains a mixed compound (aqueous solution) containing the dopant, an organic solvent for dissolving the compound, an organic solvent dissolved in the organic solvent, and viscosity of the semiconductor dopant liquid source. The adhesive, the inorganic powder having a larger diameter than the dopant, and the semiconductor dopant liquid source may further contain water.

When the P-type semiconductor dopant liquid source diffuses the P-type dopant on the semiconductor substrate, as the compound contained in the dopant, for example, boric acid, aluminum lactate, and the like are suitably used.

When the N-type semiconductor dopant liquid source diffuses the N-type dopant on the semiconductor substrate, as the compound contained in the dopant, for example, pyrophosphoric acid is suitably used.

The organic solvent has a characteristic of dissolving a compound containing a dopant. As the organic solvent having such characteristics, for example, an organic solvent containing a component such as ethanol, acetone, or propanol as a main component is suitably used.

Tackifiers have the property of dissolving in organic solvents and imparting viscosity to a liquid source of semiconductor dopants. In addition, the tackifier also has a property that, when a semiconductor dopant liquid source is coated on a coating surface of a semiconductor substrate, the viscosity is imparted to the semiconductor dopant liquid source, thereby adjusting the surface direction along the coating surface. The characteristics of adjusting the distribution of dopants on the coated surface after the interval between adjacent inorganic powders. The tackifier also has: maintaining the semiconductor dopant liquid source to a first temperature to dry it, and accompanying evaporation of the organic solvent, depositing the semiconductor dopant liquid source between adjacent inorganic powders to maintain Distribution characteristics of dopants on the coated surface.

As the thickener having such characteristics, for example, a thickener containing cellulose or a derivative thereof as a main component is suitably used. It is more desirable to use hydroxypropyl cellulose as a thickener.

The inorganic powder has a method in which, when two semiconductor substrates are laminated, a distance between adjacent inorganic powders in the surface direction of the semiconductor substrate is adjusted by a tackifier, thereby adjusting the surface direction of the interval between the two semiconductor substrates. Distribution characteristics.

In addition, the inorganic powder also includes: after heating the dopant to a temperature higher than the first temperature to generate a second temperature of the dopant diffusion supply source, placing the two semiconductor substrates bonded by heating at the second temperature; In the peeling liquid, the characteristic that the peeling liquid penetrates between the two semiconductor substrates is maintained by maintaining the interval between the two semiconductor substrates.

As the inorganic powder having such characteristics, for example, an inorganic powder containing at least one substance selected from the group consisting of Si, SiO ₂ , SiC, and Si ₃ N ₄ as a main component is suitably used.

Moreover, as a peeling liquid which has the characteristic which peels the semiconductor substrate joined by inorganic powder, a liquid, such as a hydrofluoric acid, is used suitably.

(Manufacturing method of semiconductor dopant liquid source)

Next, a manufacturing method for manufacturing the aforementioned semiconductor dopant liquid source will be described. FIG. 6 is a flowchart of a method for manufacturing a semiconductor dopant liquid source according to the second embodiment. FIG. 7 is an explanatory diagram for explaining a method for manufacturing a P-type semiconductor dopant liquid source in the method for manufacturing a semiconductor dopant liquid source according to the second embodiment.

As shown in FIG. 6, first, a compound (aqueous solution) containing a dopant, an organic solvent for dissolving the compound, and an organic solvent (dissolution step) are generated, and the viscosity is imparted to the semiconductor dopant. The liquid mixture of the liquid source thickener (mixing step) (step S1).

In addition, as shown in FIG. 7, when a mixed solution of a P-type semiconductor dopant liquid source is generated, for example, powdered aluminum lactate is mixed with water, and the aluminum lactate is completely dissolved in water by a water bath to generate an aluminum lactate solution . At this time, as shown in Fig. 7, the lactic acid can be shortened by a water bath while stirring. Dissolution time of aluminum. Compared with organic solvents, aluminum lactate is more soluble in water. By mixing aluminum lactate in easily soluble water and mixing it with an organic solvent, a mixed liquid can be accurately produced.

In addition, as shown in FIG. 7, powdered boric acid was mixed with ethanol, and the boric acid was completely dissolved in ethanol with a water bath to generate a boric acid solution. At this time, as shown in FIG. 7, the dissolution time of the boric acid can be shortened by a water bath while stirring.

Then, as shown in FIG. 7, an aluminum lactate solution, a boric acid solution, an organic solvent, and a thickener are mixed to produce a mixed solution.

FIG. 8 is an explanatory diagram for describing a method for manufacturing an N-type semiconductor dopant liquid source in a method for manufacturing a semiconductor dopant liquid source according to the second embodiment.

As shown in FIG. 8, when a mixed solution of a P-type semiconductor dopant liquid source is generated, for example, pyrophosphate, an organic solvent, and a thickener are mixed to generate a mixed solution.

After the mixed solution is generated, as shown in FIG. 6, in order to stabilize the viscosity of the mixed solution, the mixed solution is stored under a predetermined time and a predetermined atmosphere (step S2).

After the mixed solution is stored, an inorganic powder having a larger diameter than the dopant is mixed in the mixed solution (step S3). In this way, a semiconductor dopant liquid source can be obtained.

(Manufacturing method of semiconductor device)

Next, a method for manufacturing a semiconductor device using the aforementioned semiconductor dopant liquid source will be described.

FIG. 9 is a flowchart of a method of manufacturing a semiconductor device according to the second embodiment. FIG. 10 is a schematic cross-sectional view showing a dropping step in a method of manufacturing a semiconductor device according to a second embodiment.

First, as shown in FIG. 9, a semiconductor dopant liquid source is dropped on a semiconductor substrate (step S11). For example, as shown in FIG. 10, the semiconductor substrate 2 is placed on the coating head 3, and The P-type semiconductor dopant liquid source 1-P is dropped on the coating surface 2a of the semiconductor substrate 2 through the nozzle 4 from above. As shown in FIG. 10, the P-type semiconductor dopant liquid source 1-P includes the mixed P-type dopants 11-P, the organic solvent 12, the thickener 13, and the inorganic powder 14. The P-type semiconductor dopant liquid source 1-P may further contain water and ethanol. The semiconductor substrate 2 is, for example, a silicon single crystal substrate. The semiconductor substrate 2 may be doped.

FIG. 11 is a schematic cross-sectional view showing a coating step in the method of manufacturing a semiconductor device according to the second embodiment, following FIG. 10.

After the semiconductor dopant liquid source is dropped, as shown in FIG. 9, the dropped semiconductor dopant liquid source is coated on the semiconductor substrate (step S12). For example, as shown in FIG. 11, by rotating the coating head 3 in the rotation direction r, the P-type semiconductor dopant liquid source 1-P on the coating surface 2 a of the semiconductor substrate 2 is accompanied by the The semiconductor substrate 2 rotates together. The P-type semiconductor dopant liquid source 1-P flows from the center side to the surrounding side of the coating surface 2a, and is finally coated on the entire coating surface 2a.

At this time, the viscosity at which the P-type semiconductor dopant liquid source 1-P is imparted by the tackifier 13 can adjust the speed at which the inorganic powder 14 moves toward the peripheral side of the semiconductor substrate 2. By doing so, the interval i between the adjacent inorganic powders 14 in the plane direction d of the coating surface 2a can be adjusted. By adjusting the interval i between the inorganic powders 14, the distribution of the P-type dopant 11-P on the coating surface 2a can be adjusted. For example, by adjusting the interval i between the adjacent inorganic powders 14 to be equal, the distribution of the P-type dopant 11-P on the coating surface 2a can be adjusted to be equal.

FIG. 12 is a schematic cross-sectional view showing a drying step in the method of manufacturing a semiconductor device according to the second embodiment, following FIG. 11.

After the semiconductor dopant liquid source is applied, as shown in FIG. 9, the semiconductor dopant liquid source coated on the semiconductor substrate is dried (step S13). For example, as shown in Figure 12, apply The semiconductor substrate 2 having the P-type semiconductor dopant liquid source 1-P is placed on a baking plate 5 having a heating element built therein, and the baking plate 5 is heated to a drying temperature (first temperature). By this, the organic solvent and water are almost evaporated. On the other hand, as shown in FIG. 12, the tackifier 13 is left after being precipitated (that is, cured). When the thickener 13 is precipitated, the distance i between the adjacent inorganic powders 14 can be stably maintained by the thickener 13. By doing so, the distribution of the P-type dopant 11-P on the coating surface 2a can be maintained.

After the semiconductor dopant liquid source is dried, the same steps (steps S11 to S13) are used, and the surface on the opposite side of the coating surface 2a of the semiconductor substrate 2 is a new coating surface. Semiconductor dopant liquid source.

In this way, a diffusion source cover film containing the inorganic powder 14 and the P-type dopant 11-P can be formed on the semiconductor substrate 2.

FIG. 13 is a schematic cross-sectional view showing a lamination step in the method of manufacturing a semiconductor device according to the second embodiment, following FIG. 12.

After drying the semiconductor dopant liquid source on the coating surfaces on both the front and back sides of the semiconductor substrate, a plurality of semiconductor substrates are laminated as shown in FIG. 9 (step S14). For example, as shown in FIG. 13, a plurality of semiconductor substrates 2 are stacked so that the application surfaces of the semiconductor dopant liquid sources of the same conductivity type face each other. In FIG. 13, symbols 11-N indicate N-type dopants.

When the interval between the adjacent inorganic powders 14 is not adjusted, due to the imbalance in the distribution of the inorganic powders 14, portions where the inorganic powders 14 do not exist between the semiconductor substrates 2 may occur locally. In this case, at a portion where the inorganic powder 14 does not exist locally, the space between the semiconductor substrates 2 becomes narrow due to the gravity of the semiconductor substrates 2. In this way, the interval between the semiconductor substrates 2 becomes uneven in the plane direction, and the arrangement state of the dopants between the semiconductor substrates 2 in the plane direction becomes unbalanced. As a result, it is difficult to maintain the equilibrium of the dopant diffusion.

On the other hand, in this embodiment, since the interval between the adjacent inorganic powders 14 in the plane direction d is adjusted by the thickener 13, the inorganic powder 14 can adjust the interval between the plurality of semiconductor substrates 2. Distribution in the face direction. For example, the inorganic powder 14 can adjust the distribution of the intervals between the plurality of semiconductor substrates 2 in the plane direction to a uniform distribution.

Since the uniformity of the distribution of the intervals between the semiconductor substrates 2 in the planar direction can be improved, the uniformity of the arrangement of the dopants between the semiconductor substrates 2 in the planar direction can be improved. As a result, the uniformity of the dopant diffusion can be improved.

Next, FIG. 14 is a schematic cross-sectional view showing a firing step in the method for manufacturing a semiconductor device according to the second embodiment, following FIG. 13. FIG. 15 is a graph showing a temperature change in a diffusion process in the method for manufacturing a semiconductor device according to the second embodiment.

After the semiconductor substrates are laminated, as shown in FIG. 9 described above, a firing step of removing unnecessary substances is performed (step S15). For example, as shown in FIG. 14, after processing the laminated semiconductor substrate 2, the tackifier 13 is removed after heating at the firing temperature. Specifically, as shown in FIG. 15, the laminated semiconductor substrate 2 is heated at a fixed firing temperature Ta and a fixed time t1 to remove the thickener 13. At this time, since the interval between the inorganic powders 14 has been adjusted by the thickener 13 when the P-type semiconductor dopant liquid source 1-P is coated, the P-type dopants 11-P can be balanced as much as possible. The ground is arranged on the surface of the semiconductor substrate 2.

FIG. 16 is a schematic cross-sectional view showing a deposition step in the method of manufacturing a semiconductor device according to the second embodiment, following FIG. 14.

After firing, as shown in FIG. 9, a step of depositing a dopant to generate a diffusion supply source after vitrification is performed (step S16).

For example, as shown in FIG. 16, the P-type dopant 11-P is heated by heating the P-type dopant 11-P to a deposition temperature (for example, a temperature included in the second temperature of the first embodiment), thereby heating the P-type dopant 11-P. After vitrification, a diffusion source is generated. Specifically, as shown in FIG. 15, the P-type dopants 11-P are formed by following a fixed deposition temperature Tb higher than the firing temperature Ta and a time t2 longer than the firing time t1. Heating is performed to prepare the P-type dopant 11-P as a diffusion supply source. At this time, the P-type dopant 11-P will diffuse to a shallower position.

At this time, when the P-type semiconductor dopant liquid source 1-P is coated, the interval between adjacent inorganic powders 14 has been adjusted by the tackifier 13, so the P-type dopant 11-P can be as much as possible. They are evenly arranged on the surface of the semiconductor substrate 2. In this way, the P-type dopant 11-P can be diffused as uniformly as possible. The same is true for the N-type dopants 11-N.

In addition, at this time, the upper and lower semiconductor substrates 2 are bonded to each other and become a bulk state.

FIG. 17 is a schematic cross-sectional view showing a diffusion step following FIG. 16 in the method of manufacturing a semiconductor device according to the second embodiment.

After the deposition step is performed, as shown in FIG. 9, a diffusion step is performed to diffuse the dopants to a predetermined depth (step S17). For example, as shown in FIG. 17, the P-type dopant 11-P is heated to a diffusion temperature (for example, a temperature included in the second temperature of the first embodiment) to thereby make the P-type dopant 11-P Spread to a specified depth. Specifically, as shown in FIG. 15, the P-type dopant 11-P is heated by following a fixed diffusion temperature Tc higher than the deposition temperature Tb and a time t3 longer than the deposition time t2. Thus, the P-type dopant 11-P is diffused to a predetermined depth. The same is true for N-type dopants 11-N

FIG. 18 is a schematic cross-sectional view showing a dipping step subsequent to FIG. 17 in the method for manufacturing a semiconductor device according to the second embodiment.

After the diffusion step is performed, as shown in FIGS. 9 and 18, in this peeling step, the laminated semiconductor substrate 2 is immersed in the peeling liquid 6 (step S18). At this time, as shown in FIG. 18, since the space between the semiconductor substrates 2 has been maintained by the inorganic powder 14, the peeling liquid 6 can easily permeate from the portion of the outermost inorganic powder 14 to the center side.

By doing so, it is possible to promote peeling between the semiconductor substrates 2 and shorten the peeling time.

After immersion in the peeling solution, as shown in FIG. 9, the semiconductor substrate 2 is washed, dried, and peeled from the laminated state (step S19).

Hereinafter, the functions of the second embodiment will be described.

As described above, the semiconductor dopant liquid source involved in this embodiment contains the mixed: a compound containing the dopant, an organic solvent for dissolving the compound, a solvent dissolved in the organic solvent, and a viscosity of the semiconductor dopant liquid. Source thickener, and inorganic powder with larger diameter than dopant.

When the semiconductor dopant liquid source is coated on the coating surface of the semiconductor substrate, the tackifier has the following properties: by applying the viscosity to the semiconductor dopant liquid source, it adjusts the After the interval between the inorganic powders, the distribution of the dopant on the coated surface is adjusted, and the semiconductor dopant liquid source is heated to a first temperature for drying, and the semiconductor is doped with the evaporation of the organic solvent The debris liquid source is deposited between adjacent inorganic powders to maintain the distribution characteristics of the dopant on the coated surface.

The inorganic powder has a method of adjusting the interval between the plurality of semiconductor substrates by adjusting the interval between the adjacent inorganic powders in the surface direction of the semiconductor substrate with a tackifier when the plurality of semiconductor substrates are laminated. After heating the dopant to a temperature higher than the first temperature, a second temperature of the dopant diffusion supply source is generated, and a plurality of halves that are heated by the second temperature to join When the conductor substrate is placed in the peeling liquid, the characteristics of impregnating the peeling liquid between the plurality of semiconductor substrates are maintained by maintaining the interval between the plurality of semiconductor substrates.

In this way, according to the present invention, when coating a semiconductor dopant liquid source, it is possible to adjust the distribution of the dopant on the coating surface through the viscosity of the tackifier, and heat the semiconductor dopant liquid source to At the first temperature for drying, the tackifier is precipitated between adjacent inorganic powders to maintain the distribution of dopants on the coating surface. When multiple semiconductor substrates are laminated, the The viscosity is used to adjust the interval between the inorganic powders in the plane direction, so as to adjust the distribution in the plane direction of the interval between the plurality of semiconductor substrates. The space between the semiconductor substrates allows the peeling liquid to permeate between the plurality of semiconductor substrates.

By doing so, it is possible to shorten the time required for the peeling of the semiconductor substrate while ensuring the uniformity of the dopant diffusion, thereby improving the manufacturing efficiency of the semiconductor device.

In addition, in the doped film, in order to avoid abnormal combustion caused by the rapid generation of gas caused by a large amount of binder, it is necessary to pre-bake the doped film at a fixed temperature. However, in the semiconductor dopant liquid source, since an organic solvent that does not cause abnormal combustion is used, pre-baking is not required before firing. In this way, the number of steps can be reduced to further improve manufacturing efficiency.

(Modification)

In addition to the embodiments described above, the present invention can be applied to various modifications.

FIG. 19 is a flowchart of a method for manufacturing a semiconductor dopant liquid source according to a modification. For example, as shown in FIG. 19, when manufacturing a semiconductor dopant liquid source, the mixed liquid may be stirred before it is stored (step S4). By stirring the mixture, the viscosity of the thickener can be further stabilized. Viscosity. By stabilizing the viscosity of the thickener, it is possible to more effectively ensure the uniformity of dopant diffusion when manufacturing a semiconductor device.

In addition, the mass concentration (wt%) of the inorganic powder relative to the entire semiconductor dopant liquid source may be lower than the mass concentration (wt%) of the thickener relative to the entire semiconductor dopant liquid source.

At this time, when the mass concentration of the inorganic powder is higher than the mass concentration of the tackifier, the semiconductor dopant liquid source is difficult to expand because the tackifier cannot exhibit appropriate viscosity, so even if it is desired to obtain the desired viscosity Therefore, when the material of the thickener is selected, it is difficult to adjust the viscosity of the thickener correctly.

In contrast, when the mass concentration of the inorganic powder is lower than the mass concentration of the tackifier, the tackifier can exhibit appropriate viscosity, so by selecting the material of the tackifier, the tackifier can be adjusted correctly The viscosity of the agent.

In addition, the mass concentration of the inorganic powder relative to the entire semiconductor dopant liquid source may be lower than the mass concentration of the organic solvent relative to the entire semiconductor dopant liquid source.

At this time, when the mass concentration of the inorganic powder is higher than the mass concentration of the organic solvent, since the fluidity of the semiconductor dopant liquid source is significantly impaired, even if a thickening agent is added to the fluid, There are too few fluids (organic solvents) to be used for viscous properties, which results in the tackifier not exhibiting proper viscosity.

Therefore, even if it is desired to obtain the desired viscosity and select the material of the thickener, it is difficult to adjust the viscosity of the thickener correctly. In contrast, when the mass concentration of the inorganic powder is lower than the mass concentration of the organic solvent, since a sufficient organic solvent for imparting viscosity can be ensured, the tackifier can exhibit appropriate viscosity. In this way, by selecting the material of the thickener, the viscosity of the thickener can be adjusted accurately.

In addition, the inventions related to the method for manufacturing a semiconductor device according to the first, second, and modified examples described above may be combined and implemented separately.

The specific embodiments of the present invention have been described above. These embodiments are presented as examples, and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments or modifications thereof are included in the scope or gist of the invention, and are also included in a range equivalent to the invention described in the patent application scope.

Claims (15)

A method for manufacturing a semiconductor device, comprising: a dissolving step of dissolving aluminum lactate in water to prepare an aqueous solution; a mixing step of manufacturing a mixed solution of the aqueous solution and an organic solvent; and manufacturing a semiconductor dopant liquid containing the mixed solution A coating step, after performing the mixing step, coating the semiconductor dopant liquid source containing the aqueous solution on a semiconductor substrate, thereby forming a diffusion source cover film on the semiconductor substrate; a firing step, performing the coating After the step, the semiconductor substrate is heat-treated at a first temperature in a first atmosphere to fire at least the organic solvent in the diffusion source cover film; and a diffusion step. After the firing step is performed, In a second atmosphere, the semiconductor substrate is heat-treated at a second temperature higher than the first temperature to diffuse aluminum contained in the diffusion source cover film on the semiconductor substrate, thereby forming a diffusion layer on the semiconductor substrate. . The method for manufacturing a semiconductor device according to item 1 of the application, wherein the organic solvent has a property that the aluminum lactate is not dissolved. The method for manufacturing a semiconductor device according to item 2 of the scope of patent application, wherein the organic solvent is any one of ethanol, acetone, propanol, or alcohol. The method for manufacturing a semiconductor device according to item 3 of the scope of patent application, wherein the first atmosphere in the firing step is an oxidizing atmosphere. The method for manufacturing a semiconductor device according to item 4 of the scope of patent application, wherein the second atmosphere in the diffusion step is the oxidation atmosphere. The method for manufacturing a semiconductor device according to item 5 of the scope of patent application, wherein the oxidizing atmosphere is an oxygen-containing atmosphere. The method for manufacturing a semiconductor device according to item 6 of the application, wherein the coating step applies the semiconductor dopant liquid source on the semiconductor substrate by a spin coating method. The method for manufacturing a semiconductor device according to item 7 of the scope of patent application, wherein the first temperature in the firing step is in a range of 400 ° C to 600 ° C. The method for manufacturing a semiconductor device according to item 8 of the scope of patent application, wherein the second temperature in the diffusion step is in a range of 1000 ° C to 1300 ° C. The method for manufacturing a semiconductor device according to item 7 of the scope of patent application, wherein the semiconductor substrate is an N-type silicon wafer. The method for manufacturing a semiconductor device according to item 10 of the scope of patent application, further comprising a peeling step, and after performing the diffusion step, peeling off the film remaining on the semiconductor substrate with a peeling liquid. The method for manufacturing a semiconductor device according to item 11 of the scope of patent application, wherein the stripping solution is hydrofluoric acid. The method for manufacturing a semiconductor device according to item 11 of the application, wherein the semiconductor dopant liquid source further comprises: a tackifier that dissolves in the organic solvent and imparts viscosity to the semiconductor dopant liquid source, And a plurality of inorganic powders, in the firing step, in a state where the two semiconductor substrates face each other so that the diffusion source cover films of the two semiconductor substrates are in contact, the two The semiconductor substrate is heat-treated at the first temperature. In the diffusion step, the two semiconductor substrates are heat-treated at the second temperature in the second atmosphere. The inorganic powder has: When stacking the two semiconductor substrates, the interval between the adjacent inorganic powders in the plane direction of the semiconductor substrate is adjusted by the tackifier, so as to adjust the interval in the plane direction of the interval between the two semiconductor substrates. Distribution characteristics, the inorganic powder also has: after heating the dopant above the first temperature to generate the second temperature of the dopant diffusion supply source, When the two semiconductor substrates that are joined by heating at the second temperature are placed in the peeling liquid, the peeling liquid is impregnated between the two semiconductor substrates by maintaining a gap between the two semiconductor substrates. In the stripping step, the two semiconductor substrates facing each other are separated. The method for manufacturing a semiconductor device according to item 13 of the scope of patent application, wherein the main component of the thickener contains cellulose, a fiber bundle derivative, or hydroxypropyl cellulose. The method for manufacturing a semiconductor device according to item 1 of the scope of patent application, wherein pre-baking is performed between the coating step and the firing step, and the semiconductor substrate is heat-treated at a third temperature lower than the first temperature. Therefore, at least the organic solvent and the water in the diffusion source cover film are evaporated.