JP2895438B2 - Standard piece manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for depositing a high quality barrier film on a standard piece of a silicon wafer, and forming a borosilicate glass (BPSG) film 2 or a phosphosilicate glass (P) on the standard piece.
SG) maintaining the stability of the phosphorus impurity concentration of the film,
It relates to a method for producing a kind of standard piece (Golden Wafer).

[0002]

2. Description of the Related Art As a result of high integration of integrated circuits, uneven terrain (Severe) is formed on the surface of a semiconductor wafer.
In particular, in the case of manufacturing a multi-layer metal integrated circuit, a multi-layer metal and an insulating layer are alternately deposited and etched, so that a beak-shaped terrain is formed. I can't escape. The formation of such terrain affects subsequent manufacturing processes and results in poor results, for example, when the depth of focus of the microscopic exposure is too deep, distorting the photoresist image, or etching residues. To form a metal wire short circuit (shor
t). The current planarization techniques used to resolve uneven terrain and terrain include silicon dioxide flow or bias sputtered silicon dioxide (Bias Sputte).
rd Silicon Dioxide) method. Among them, the silicon dioxide flow method mixes a boron impurity or a phosphorus impurity in silicon dioxide, and then,
Chemical vapor deposition (CVD: Chemical Vapo)
r Deposition) on a silicon crystal, a borophosphate glass (BPSG: Boronphospho).
Silicate Glass or phosphosilicate glass (PSG: Phosphosilicate Gl)
ass), and the high temperature (about 90
(0 ° C. to 930 ° C.), which achieves the effect of flattening the topography and terrain by the property of flowing at the time. As can be seen, in order to effectively apply the silicon dioxide flow method to flatten the topography and terrain, the impurity concentration of borophosphate glass (BPSG) or phosphosilicate glass (PSG) must be stabilized. In other words, if it is unstable and its concentration decreases with time, it is disadvantageous for flattening. Furthermore, the side wall (Side)
Wall Spacer or other etch rates during manufacturing that do not require silicon dioxide flow (E
In order to control the tch rate, borophosphate glass (BPSG) or phosphosilicate glass (PSG)
It is required to stabilize the impurity concentration of G).

[0003] In view of the importance of borophosphate glass (BPSG) or phosphosilicate glass (PSG) concentration stability to the topography and terrain flattening of highly integrated integrated circuits, generally a standard piece is first manufactured. , Followed by borophosphate glass (BPSG) or phosphosilicate glass (P
SG) concentration measurement is in progress.

[0004] As shown in Fig. 1, a conventional standard piece manufacturing process is as follows. (A) First, one silicon wafer is prepared, and (B) one more boric acid is formed by chemical vapor deposition (CVD). Depositing a salt glass (BPSG) or phosphosilicate glass (PSG) insulating layer on the silicon wafer, followed by annealing in a high temperature furnace;
(C) Thereafter, the standard piece is placed in a nitrogen gas box, and the above steps for preventing the impurity concentration of borophosphate glass (BPSG) or phosphosilicate glass (PSG) from decreasing with time are included.

In the production of traditional standard pieces, borophosphate glass (BPSG) or phosphosilicate glass (PSG)
G) It is necessary to place a standard piece in a nitrogen gas box in order to keep the impurity concentration of the film constant. This is not economical, and it is not economical. Could be destroyed unless carefully placed in a nitrogen gas box (ie, a drop in the carrier concentration of the borophosphate glass (BPSG) or phosphosilicate glass (PSG) insulating layer on the standard piece was formed). ).
Therefore, in order to avoid human error, the standard piece to be used must always be taken out of the nitrogen gas box and exposed to the atmosphere, so that borophosphate glass (BPSG)
Alternatively, a decrease in the impurity concentration in the phosphosilicate glass (PSG) film was inevitable.

[0006]

SUMMARY OF THE INVENTION In order to overcome the drawbacks of the above-mentioned conventional method for producing standard pieces, the present invention provides a kind of economical and convenient method for producing standard pieces. In this method, a high-quality barrier film (Barrier Film) is deposited on a standard piece to maintain the stability of the borophosphate glass (BPSG) or phosphosilicate glass (PSG) impurity concentration on the standard piece. To eliminate the need to leave the standard piece in nitrogen gas, that is, to maintain the quality of the standard piece while leaving it in the air.

[0007]

According to the first aspect of the present invention, a silicon wafer is first prepared, and thereafter, borophosphate glass (BPSG) is formed by chemical vapor deposition (CVD).
Alternatively, phosphosilicate glass (PSG) is deposited on a silicon wafer, and finally, tri-silicon tetranitride (Si) is plasma-assisted to assist chemical vapor deposition (CVD).
_A 3N ₄ ) film is deposited on a borophosphate glass (BPSG) or phosphosilicate glass (PSG) film to form a barrier film, and a standard piece is completed.

According to the second aspect of the present invention, trisilicon tetranitride (S
Chemical vapor deposition (CVD: Chemical Vapor) using a plasma of i ₃ N ₄ ) barrier film.
Deposition is deposited to assist.

According to the third aspect of the present invention, the reaction temperature at the time of depositing the barrier film is set at about 300 ° C. to 500 ° C.

In the invention of claim 4, the reaction pressure at the time of depositing the barrier film is set to about 2 to 8 torr.

In the present invention, the reaction gas at the time of depositing the barrier film includes a silane (SiH ₄ ) gas, and the flow rate of the silane gas is 20 to 60 sccm.
And further contains ammonia (NH ₃ ) gas, and the gas flow rate of this ammonia gas is 0 to 80 scc
m, and contains nitrogen (N ₂ ) gas, and the gas flow rate of this nitrogen gas is 1000 to 3000 sccm.

In the invention of claim 6, the injection frequency efficiency of the reaction gas at the time of depositing the barrier film is set to about 100 to 500 watts.

In the invention of claim 7, the distance between the silicon wafer and the reactive gas injection port at the time of depositing the barrier film is about one.
50 to 750 mils.

In the invention of claim 8, a borophosphate glass (BPSG) film or a phosphosilicate glass (PSG)
G) Trisilicon tetranitride (Si) deposited on film
₃ N ₄ ) or other barrier film thickness of about 50
Angstrom and above.

In the ninth aspect of the present invention, trisilicon tetranitride (S
i ₃ N ₄₎ barrier film instead of silicon nitride (Si
N) Depositing a barrier film.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of the present invention comprises the steps of (1) first preparing a silicon wafer, and (2) thereafter using borophosphate glass (BPSG) or phosphosilicate using chemical vapor deposition (CVD). Salt glass (PSG) is deposited on a silicon wafer. (3) Finally, plasma assisted chemical vapor deposition (CVD) assists in trisilicon tetranitride (Si _3).
N ₄ ) depositing a film on a borophosphate glass (BPSG) or phosphosilicate glass (PSG) film;
The standard piece is completed by the above steps (1) to (3).

In the present invention, trisilicon tetranitride (Si
_{3 N 4)} film key points step and without the deposition of, assist four nitride three silicon (Si 3 _{N 4)} chemical vapor deposition method using plasma in deposition of the film (CVD), the conditions of use following It is like. That is, the reaction temperature is 300 to 500 ° C., the reaction pressure is 2 to 8 torr,
The reaction gas is silane (SiH ₄ ) gas, ammonia (NH)
₃ ) Gas and nitrogen (N ₂ ) gas are included, and the flow rate of each gas is 20-60 sccm and 0
８０80 sccm and 1000-3000 sccm, the injection frequency efficiency of the reaction gas is 100-500 watts, and the distance of the silicon wafer from the gas injection port is about 150-75.
0 mil (1 mil = 1/1000 centimeter).

In the present invention, trisilicon tetranitride (Si
_{3 N 4)} Key points of the operational means the difference in thickness of the film and without, i.e., ahead each borophosphate glasses (BP
SG) or phosphosilicate glass (PSG) films with different thicknesses of tri-silicon tetranitride (Si ₃ N ₄ ) films deposited, followed by X-ray fluorescence spectroscopy (XRF: X
-Ray Fluorescence Spectro
metry) or Fourier transform infrared spectrometer (FTI)
R: Fourier Transform Infra
time of the boron or phosphorus impurities in the borophosphate glass (BPSG) or phosphosilicate glass (PSG) film with a surveying instrument such as red Spectrometry, time, thickness of trisilicon tetranitride (Si ₃ N ₄ ) film By measuring the decrease in the concentration percentage of impurities with
Based on this, the standard value of the standard piece is calculated, and used for the work of adjusting the impurity concentration of the other standard pieces at a later date.

The standard piece manufactured by the method of the present invention has the following excellent points. That is, (1) it can be easily obtained, (2) the required equipment is reduced, there is no need to provide a nitrogen gas box, and (3) one protective film is formed on the standard piece, so that boric acid on the standard piece (4) In addition to stabilizing the impurity concentration of salt glass (BPSG) or phosphosilicate glass (PSG), it also prevents contamination by other fine particles.
It is a more convenient manufacturing method than the conventional one and increases the product competitiveness.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 2, according to the present invention, one silicon wafer 1 is first provided (as in A) as in the conventional method of manufacturing a standard piece. Then, a chemical vapor deposition method (CVD: Chemical Vapor Depos)
It is applied to borophosphate glass (BPS)
G) Deposit film 2 or phosphosilicate glass (PSG) film on silicon wafer 1 (as in B). Subsequently, plasma-assisted deposition by chemical vapor deposition is used to assist the deposition of trisilicon tetranitride (Si ₃ N ₄ ) film 3 or silicon nitride (SiN) film into borophosphate glass (BPSG) film 2 or phosphosilicate acid. Deposit on salt glass (PSG) film (as in C). Among them, the reaction conditions for depositing the trisilicon tetranitride (Si ₃ N ₄ ) film 3 are as follows. That is, the reaction temperature is 300 ° C. to 500 ° C., the reaction pressure is 2 to 8 torr, the reaction gas and the gas flow rate are silane (SiH ₄ ) gas,
The gas flow rate is 20-60 sccm, and ammonia (N
H ₃ ) gas, its gas flow rate 0 to 80 sccm, and nitrogen (N ₂ ) gas, its gas flow rate 1000 to 3000 scc
m, the injection frequency efficiency of the reaction gas is about 100 to 500 watts, and the distance of the silicon wafer from the gas injection port is about 150 to 750 mils. Under the above reaction conditions, the deposition of the trisilicon tetranitride (Si ₃ N ₄ ) film 3 on the borophosphate glass (BPSG) film 2 or the phosphosilicate glass (PSG) film is completed. The thickness of the trisilicon tetranitride (Si ₃ N ₄ ) film 3 is 50 Å or more. Another method is to deposit a silicon nitride (SiN) film, and the reaction conditions are as follows. That is, the reaction temperature is from 300 ° C. to 500 ° C., and the reaction pressure is from 2 to 8 to
rr, a reaction gas and its gas flow rate are respectively silane (SiH ₄ ) gas, its gas flow rate of 20 to 60 sccm,
And ammonia (NH ₃ ) gas, the gas flow rate of which is 0 to 80
sccm and nitrogen (N ₂ ) gas, and its gas flow rate 100
The injection frequency efficiency of the reaction gas is about 100 to 500 watts, and the distance of the silicon wafer from the gas injection port is about 150 to 750 mil (mil).
s). Under the above reaction conditions, silicon nitride (S
Complete deposition of iN) film on borosilicate glass (BPSG) film 2 or phosphosilicate glass (PSG) film. The thickness of this silicon nitride (SiN) film is 50 Å or more.

FIG. 3 shows borophosphate glass (BPS) of barrier films of different thicknesses using the surveying instrument of the present invention.
G) Impurity concentration measurement for Film 2 or phosphosilicate glass (PSG) film. In brief, the effective measurement depth of the surveying instrument is silicon nitride (S
iN) Decreases as the film thickness increases, and thus, for thicker barrier films 3, the impurity concentration for borophosphate glass (BPSG) film 2 or phosphosilicate glass (PSG) film The effective depth d _{1 of the} measurement is relatively shallow, and conversely, for a thin barrier film 3, a borophosphate glass (BPSG) film 2 or a phosphosilicate glass (P
SG) Effective depth d ₂ of impurity concentration measurement for film
Is relatively deep. Therefore, in the function curve diagram of the measured impurity concentration and time, it can be compared whether or not the impurity concentration is stable from the same curve (barrier film thickness is constant), but different curves (barrier film thickness). Is different), it is not possible to directly compare the concentration percentage between each other from the measured values.

FIG. 4 shows trisilicon tetranitride (S) of different thicknesses.
and i 3 _{N 4)} film (material measure deposition of the barrier film 3), and those not deposited a diagram showing by comparing the change in the descending with time of the concentration of phosphorus impurities. FIG.
The horizontal axis in the graph is the time axis (unit is time), the change value of the time from the completion of manufacture of the standard piece to the measurement is displayed, and the vertical axis is the phosphorus impurity concentration axis (unit is arbitrary), and the phosphosilicate glass ( PS
G) shows the change value of the phosphorus impurity concentration in the film. In addition, different symbols in the figures indicate values when the barrier films (for example, trisilicon tetranitride (Si ₃ N ₄ )) have different thicknesses. For example, phosphosilicate glass (PS
G) Trisilicon tetranitride (Si) deposited on film
The thickness of ₃ N _4), 50 Å, 100 Å, 150 Å, 200 Å, 250 Å, or four nitride three silicon _(Si 3 _{N 4)} which does not deposit a film (i.e. four nitride three silicon _(Si 3 N ₄ ), the thickness of which is 0 angstrom), wherein the symbol “○” in the figure indicates trisilicon tetranitride (Si ₃ ) on a phosphosilicate glass (PSG) film.
N ₄ ) Film thickness is 50 Å, '△'
The symbol is a tri-silicon tetranitride (Si ₃ N ₄ ) film having a thickness of 100 Å, the symbol “◆” is a tri-silicon tetranitride (Si ₃ N ₄ ) film having a thickness of 150 Å, and the symbol “★” is tetra-nitriding The thickness of the trisilicon (Si ₃ N ₄ ) film is 200 angstroms, the symbol “□” indicates the thickness of the trisilicon tetranitride (Si ₃ N ₄ ) film is 250 angstroms, and the symbol “●” indicates the silicon trinitride (Si ₃ N ₄ ). ₃ N
₄ ) Representative of the case where the thickness of the film is 0 Å, as can be seen from the figure, when there is no tri-silicon tetranitride (Si ₃ N ₄ ) barrier film on the uppermost layer of the standard piece, that is, tri-silicon tetranitride When the thickness of the (Si ₃ N ₄ ) film is 0, the phosphorus impurity concentration of the phosphosilicate glass (PSG) of the standard piece left in the air continuously drops with time. On the other hand, when one barrier film is deposited on the standard piece, the phosphorus impurity concentration is very stable and does not change with time. FIG.
Represents trisilicon tetranitride (Si ₃ N ₄ ) deposited on a standard piece
FIG. 6 is a diagram showing the relationship between the thickness of the film (barrier film) and the degree of decrease in the phosphorus impurity of the phosphosilicate glass (PSG) in the standard piece. As shown in FIG. 5, the relation between the degree of decrease in the impurity concentration and the thickness of the barrier film. Exhibits a substantially linear relationship, ie, as the thickness of the barrier film increases, the effective measurement depth of the phosphorus impurity concentration of the phosphosilicate glass (PSG) decreases, and the relative measured concentration Becomes smaller. Conversely, the thinner the barrier film, the deeper the effective measurement depth of the phosphorus impurity concentration of the phosphosilicate glass (PSG), and the higher the relative measured concentration. And the relational expression becomes one linearity. Therefore, the following conclusions are drawn from FIG. 4 and FIG. (1) By the method of depositing a barrier film of the present invention,
The stability of the impurity concentration in the standard piece of borophosphate glass (BPSG) film 2 or phosphosilicate glass (PSG) film can be maintained, and the thickness of the barrier film is borophosphate glass (BPSG) film 2 or phosphorus silicate glass. It is not a sensitive factor for the stability of the impurity concentration of the phosphate glass (PSG) film. (2) Since the degree of decrease in the impurity concentration and the thickness of the barrier film exhibit one linear relationship, they become standard reference numeral data at a later date. That is, if the thickness of the barrier film is measured, the corresponding decrease in the impurity concentration is obtained. The degree can be calculated, and the time and cost for measuring the impurity concentration again can be saved.

FIG. 6 shows trisilicon tetranitride (S) of different thicknesses.
Comparison of the time-dependent change in the boron ion impurity concentration in a standard piece on which an i ₃ N ₄ ) film (barrier film 3) is deposited and a standard piece on which no silicon trinitride (Si ₃ N ₄ ) film is deposited FIG. The horizontal axis is the time axis (unit is time), the vertical axis is the boron impurity concentration axis,
The unit is arbitrary. As can be seen from the figure, tri-silicon tetranitride (S) was deposited on a borophosphate glass (BPSG) film.
In a standard piece on which no i ₃ N ₄ ) film (barrier film) was deposited, the boron ion impurity concentration decreased over time, but a silicon trinitride (Si ₃ N ₄ ) film (barrier film) was deposited. In that case, the boron ion impurity concentration remains stable. Further, FIG. 7 is a graph showing the relationship between the decrease in the boron ion impurity concentration in the borophosphate glass (BPSG) film of the standard piece formed with the trisilicon tetranitride (Si ₃ N ₄ ) film (barrier film) having different thicknesses. As shown, the relationship between the degree of the decrease in the impurity concentration and the thickness of the barrier film exhibits almost one linear relationship, and therefore, here again, the above-mentioned thing is proved with reference to FIG. 4, and the conclusion obtained from FIG. Proven.

FIG. 8 shows the percentage concentration of phosphorus impurities in phosphosilicate glass (PSG) versus hydrogen phosphine (P
H ₃ ) is a relational diagram of a change in gas flow rate. In the figure, a symbol “代表” represents a case where there is no barrier film on a standard piece, and a symbol “◇” represents a case where a barrier film is present on a standard piece. As can be seen from the figure, when there is no barrier film on the standard piece, the percentage concentration of phosphorus impurities is phosphine (P
It has almost one linear relationship with the flow rate of the H ₃ ) gas. As the flow rate of the phosphine (PH ₃ ) gas increases, the percentage concentration of the phosphorus impurity relatively increases. In addition, between those with and without the barrier film on the standard piece,
The value of the phosphorus impurity percentage concentration with respect to the flow rate of the phosphine (PH ₃ ) gas differs substantially by a constant value.

[0025]

The standard pieces produced by the method of the present invention are:
(1) Easy to obtain, (2) Reduced equipment required, no need to provide nitrogen gas box, (3) Boronate glass on standard piece by forming one protective film on standard piece In addition to stabilizing the impurity concentration of (BPSG) or phosphosilicate glass (PSG), it also prevents contamination by other fine particles, and (4) is a more convenient manufacturing method than conventional methods and increases product competitiveness. In addition, (1) By the method of depositing the barrier film of the present invention,
The stability of the impurity concentration in the standard piece of borophosphate glass (BPSG) film 2 or phosphosilicate glass (PSG) film can be maintained, and the thickness of the barrier film is borophosphate glass (BPSG) film 2 or phosphorus silicate glass. It is not a sensitive factor for the stability of the impurity concentration of the phosphate glass (PSG) film. (2) Since the degree of decrease in the impurity concentration and the thickness of the barrier film exhibit one linear relationship, they become standard reference numeral data at a later date. That is, if the thickness of the barrier film is measured, the corresponding decrease in the impurity concentration is obtained. The degree can be calculated, and the time and cost for measuring the impurity concentration again can be saved.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a manufacturing process of a traditional standard piece.

FIG. 2 is a view showing a manufacturing process of a standard piece of the present invention.

FIG. 3 shows a borophosphate glass (BPSG) film or a phosphosilicate glass (PS) film for a standard piece having a barrier film of different thickness using a surveying instrument of the present invention.
G) Illustration of measurement of impurity concentration in film.

FIG. 4. Phosphorous impurity contamination between a standard piece of trisilicon tetranitride (Si ₃ N ₄ ) film (barrier film 3) of different thickness and a non-deposited one produced by the method of the present invention. It is a comparison figure of a fall change with time of density.

FIG. 5: Trisilicon tetranitride (Si ₃ N ⁴ ) film (barrier film) deposited on a standard piece manufactured according to the invention
FIG. 4 is a graph showing the relationship between the thickness of a sample and the degree of decrease in phosphorus impurities of a phosphosilicate glass (PSG) in a standard piece.

FIG. 6 shows a standard piece deposited with different thicknesses of trisilicon tetranitride (Si ₃ N ₄ ) film (barrier film) and a trisilicon tetranitride (Si ₃ N ₄ ) film not deposited according to the method of the present invention. FIG. 4 is a comparison diagram showing a relationship between a boron ion impurity concentration in a standard piece and a decrease with time.

FIG. 7 shows a standard piece formed with trisilicon tetranitride (Si ₃ N ₄ ) films (barrier films) of different thicknesses according to the method of the present invention, and a decrease in boron ion impurity concentration in borophosphate glass (BPSG) film. It is a relation display figure with a degree.

FIG. 8 is a graph showing the relationship between the percentage concentration of phosphorus impurities in phosphosilicate glass (PSG) and the flow rate of hydrogen phosphine (PH ₃ ) gas in a standard piece according to the method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Silicon wafer 2 ... Borosilicate glass (BPSG) film or phosphosilicate glass (PSG) film 3 ... Barrier film (trisilicon tetranitride (Si
₃ N ₄₎ film or a silicon nitride (SiN) film)

Claims (8)

(57) [Claims] First, a silicon wafer is prepared, and thereafter, borophosphate glass (BPSG) or phosphosilicate glass (PSG) is deposited on the silicon wafer by chemical vapor deposition (CVD). In addition, plasma assisted chemical vapor deposition (CVD) is used to assist tri-silicon tetranitride (Si ₃ N ₄ ) film in borophosphate glass (BP).
SG) or phosphosilicate glass (PSG) film to form a barrier film to form a standard piece (Golde
n Wafer), a standard strip manufacturing method. 2. The reaction temperature when depositing a barrier film is 30.
The method for producing a standard piece according to claim 1, wherein the temperature is from about 0 ° C. to about 500 ° C. 3. The method for producing a standard piece according to claim 1, wherein the reaction pressure during deposition of the barrier film is about 2 to 8 torr. 4. A reaction gas for depositing a barrier film includes silane (SiH ₄ ) gas, a gas flow rate of the silane gas is 20 to 60 sccm, and further includes an ammonia (NH ₃ ) gas. gas flow rate, and 0～80Sccm, and nitrogen _{(N 2)} is intended to include gas, gas flow rates of the nitrogen gas, and 1000～3000Sccm, manufacturing method of the material measure according to claim 1. 5. The method for producing a standard piece according to claim 1, wherein the injection frequency efficiency of the reactive gas at the time of depositing the barrier film is about 100 to 500 watts. 6. The method according to claim 1, wherein the distance between the silicon wafer and the reactive gas injection port when depositing the barrier film is about 150 to 750 mils. 7. The method of claim 1, wherein the thickness of tri-silicon tetranitride (Si ₃ N ₄ ) deposited on the borophosphate glass (BPSG) film or the phosphosilicate glass (PSG) film is about 50 Å or more. 2. A method for producing a standard piece according to item 1. 8. The method for manufacturing a standard piece according to claim 1, wherein a silicon nitride (SiN) barrier film is deposited instead of the trisilicon tetranitride (Si ₃ N ₄ ) barrier film.