JPH04174342A - Method for evaluating performance of liquid for forming sog file and its performance evaluation mechanism as well as manufacture of semiconductor device utilizing its performance evaluation method - Google Patents

Abstract

PURPOSE:To prevent failure due to coating unevenness by dripping a liquid for forming an SOG (spin-on-glass) film on a semiconductor substrate where an SiO2 ground film is formed and then judging if a spread diameter D per dip (approximately 0.005ml) is equal to or longer than 6.5mm. CONSTITUTION:A liquid for forming an SOG film is dripped on a semiconductor substrate where an SiO2 ground film is formed and a spread diameter D per drip (approximately 0.005ml) is measured for judging if D is equal to or longer than 6.5mm, where the liquid for forming the SOG film generally consists of alkyl silanol and an organic solvent and the concentration of alkyl silanol is normally 5 - 20%. Also, it is desirable that a semiconductor substrate which is used for evaluating performance of liquid for forming the SOG film should be equal to what coats solution actually. The solution for forming the SOG film is dripped from a location which is approximately 3 - 5mm above onto the semiconductor substrate and the diameter D can be measured by slide calipers.

Description

[Detailed Description of the Invention] (a) Industrial Application Field This invention is applicable to SOG film (Spin On Glass).
When manufacturing an SOG film (SiO film) using a film forming solution, the method for evaluating the performance of the SOG film forming solution, its performance evaluation mechanism, and its performance evaluation method are used. The present invention relates to a method for manufacturing a semiconductor device.

(b) Problems to be Solved by the Prior Art and the Invention SOG film forming solutions have conventionally been used as coating materials for flattening unevenness on semiconductor substrates and for forming interlayer insulating films. The SOG film forming solution consists of an alkylsilanol and an organic solvent, and because of its chemically unstable nature, it is often spin-coated onto a wafer and then deposited as shown in Figure 2 (λ). In the scribe line 21, a portion 22 where the solution was repelled and could not be applied, that is, so-called uneven coating occurred. This uneven coating is mainly caused by the scribe line 21 having a high level difference d of 1.5 μm or more in the base, as shown in FIG. 2(b). The inventor has discovered that the larger the size, the more severe the coating unevenness becomes.

In addition, in FIG. 2, 23 is an St substrate (wafer) having a SiO2 base film (not shown) on the entire upper surface,
24 is 5OGI!, which is spin-coated on the St substrate 23 via a base film. The LSI or chip is formed on a Siow film created by baking the forming solution at a temperature of, for example, 420° C. for about one hour.

Further, FIGS. 7(a) and 7(b) show two types A and B of scribe lines formed on a semiconductor substrate used in this field. In the type A shown in FIG. 7(a), the St substrate 23 covering the eaves 23a is depicted.

Therefore, in this field, it is necessary to use a suitable S for the semiconductor substrate used.
It is necessary to select and utilize solutions for forming OG films, and it has been desired to find a simple method for selecting and evaluating solutions for forming SOG films.

(c) Means for solving the problem The present invention provides a semiconductor substrate on which a SiO2 base film is formed.
Drop the SOG film forming solution and measure the spreading diameter per drop.
．． 0O5,w12)
This provides a method for evaluating the performance of a G film forming solution.

The SOG film forming solution used in this invention generally consists of an alkylsilanol and an organic solvent.

Alkylsilanols have the formula Rn-51(OH)4-n(
However, R represents an alkyl group, and n is 1 to 3). The organic solvent is not particularly limited. However, according to the knowledge of the inventor of this invention,
We have found that propylene glycol monopropyl ether, butyl cellosolve, ethanol, and the like are preferred. The concentration of alkylsilanol is usually 5-20%. The semiconductor substrate used for performance evaluation of the SOG film forming solution is preferably the same as that on which the solution is actually applied. That is, the semiconductor substrate used is one on which a SiO2 base film is formed by the CVD method or the plasma oxidation method. The semiconductor substrate may or may not have scribe lines. However, as will be described later, the SOG film forming solution selected by the evaluation method of the present invention has the effect of preventing uneven coating even when a semiconductor substrate is formed with a scribe line having a step difference d of 1.5 μm or more. show.

In the performance evaluation method of the SOG film-forming solution of the present invention, the SOG film-forming solution is used, for example, in a syringe [see FIG. 8].
The liquid is dropped onto the semiconductor substrate from above for approximately 3 to 5 ms using the above-described method. The amount per drop is preferably approximately 00051e. Once the droplet has expanded sufficiently, its diameter is measured. The diameter can be measured using a physical method such as a caliper (see FIG. 9). Alternatively, the measurement may be performed using an optical microscope equipped with an eye [see Figure (2)] or by optical means.

From the above point of view, the apparatus includes a dropping means for dropping the SOG film forming solution onto the semiconductor substrate, and a diameter measuring means for measuring the spreading diameter of each drop of the dropped SOG film forming solution. Ta SOG! A mechanism for evaluating the performance of l-forming solutions is provided.

Next, the results of tests conducted when discovering a method for evaluating the performance of the SOG film forming solution of the present invention will be shown.

As the solution for forming the coated SOG film for testing, the solutions listed in the following table from Tokyo Ohka Kogyo Co., Ltd. were used.

(Left below) *P, G, P are propylene glycol monopropyl ether B, C is butyl cellosolve.

FIG. 3 shows the severity of coating unevenness of various types (8%, 15%, 16% and 17%) of SOG solutions with respect to the scribe line step d.

Furthermore, FIG. 5 shows the wettability (ease of spreading of droplets) on the base film for various SOG solutions.

From Fig. 3.5, it was found that the following relationship holds indirectly.

In other words, the wettability of the SOG solution (the spreading diameter D of 'a)
It was found that the larger the value, the better the coating unevenness resistance against scribe line step difference d.

In addition, it was found that the degree of this difference differed depending on the underlying film. At this time, using a mixed gas of S I H4, N, and O,
A SiOz base film formed by a plasma oxidation method at a low temperature of about 00 to 400 degrees Celsius is better than a Sins base film formed by a plasma oxidation method at a low temperature of about 350 to 400 degrees Celsius using a mixed gas of tetraethylene and oxygen. It can be seen that the wetting properties of the SOG film forming solution are better.

In summary, the size of the scribe line step d depends on (i) the concentration of solute in the SOGl forming solution and the difference in solvent (see Figure 3);

(ii) Also, the expanded diameter D of the droplet (Expanded
Diai-eter of a drop) (see No. 5r!lJ).

From this relationship, when applying the SOG solution shown in Fig. 5, a solution for forming 5OGlil that spreads and has a diameter of 8.511 or more in the drop test, the step d of the scribe line is about 2 to 3
It was found that there was no uneven application of the SOG film forming solution even when there was a height difference of 1.

Moreover, from another point of view, the present invention provides SiO2 on a single or multiple semiconductor substrates using a CVD method or a plasma oxidation method.
y base film is formed, and the SOG film forming solution is dropped on a part of the semiconductor substrate on which the Sif2 base film is formed, and 1ii
Measure the spreading diameter per li, select a coating solution with D≧8.5xx or more (however, one drop is about 0,005 x L2), and use the selected coating solution to coat the above S i O
Provided is a method for manufacturing a semiconductor device using a method for evaluating the performance of an SOC* forming solution, which comprises spin-coating the solution onto a base film and then subjecting it to heat treatment to flatten the semiconductor substrate.

(d) Examples The present invention will be described in detail below based on examples shown in the drawings. Note that this invention is not limited by this.

A method for evaluating the performance of a solution for forming an SOG film and a method for manufacturing a semiconductor substrate will be described below with reference to the block diagram shown in FIG.

Before applying the t,soc film forming solution, the scribe line level difference of a semiconductor substrate sample for LSI is measured (step 601).

At this time, (a) if the scribe line step difference d is 1.5 μm or more (step 602), evaluate the 5OGI [forming solution]. On the other hand, (b) step height difference d is 1.5 um
In the following cases (step 609), performance evaluation of the SOG film forming solution is unnecessary and coating is performed (step 6
05).

2 Evaluation test and selection of combination of SOG film forming solution and base film (c) Base 1K (1K) for evaluation of SOG film forming solution
Plasma S i Otll ) is deposited on the bare Si substrate (step 603).

At this time, one drop (0,005 cc) of SOG film forming solution is dropped onto the plasma S i O film, and a combination is selected in which the spread diameter of the drop is 8,5JI11 or more (
Step 606).

Next, using a solution for forming an SOG film and a solution evaluated by changing the covering type of the base film, the scribe line step difference d or 2
The results are shown when spin coating was performed on a ~3 μm LSI substrate and heat treatment was performed.

FIG. 8 shows a dropping device for a solution for forming an SOG film.

In FIG. 8, the apparatus consists of a micrometer 82 connected to an approximately 2zQ syringe 81 containing a solution 80 for forming an SOG film, and a main body of the apparatus. Further, the main body of the device includes a support base 83, an upright portion 84, and a syringe fixing portion 85 coupled thereto.

86 is a fixing screw, 87 is rubber, 88 is a wafer, and 90 is an injection needle, the outer diameter of which is 0.7 zm. The distance between the tip of the needle and the wafer surface is preferably 3 to 5111 degrees. The syringe 81 is removably fixed to the device, and by rotating the upper rotating part of the micrometer 82 in the direction of the arrow, the pushing rod (piston) 89 moves slightly in the direction A to push out the piston, causing just a droplet to drop. enable. The syringe has a rubber 87 attached to the tip of the piston to prevent it from dropping due to the piston's own weight.

The diameter measuring device is shown in FIGS. 9 and 10 below.

The one in FIG. 9 is a caliper 99, which makes it possible to measure the diameter of one drop of the SOG film forming solution (approximately 0,005zQ 92) spread on the wafer 88.

In the one shown in FIG. 10, an ordinary microscope 93 is equipped with a micrometer 94, and measurements are made by reading the scale reflected in the field of view S. The micrometer used had a maximum scale of 20ii and an accuracy of ±0°0Smx or higher.

(E) Effects of the Invention As described above, according to the present invention, by using an SOG film forming solution that passed the performance evaluation test of the SOG film forming solution, steps on the scribe line can be reduced in LSI manufacturing. Regardless of the size, it is effective in preventing defects due to uneven coating.

[Brief explanation of the drawing]

Figure 1 is a characteristic diagram showing the coating unevenness α in the relationship between the SOG film forming solution and the step d of the scribe line, and Figures 2 (a) and (b) are an explanatory diagram of the configuration and main parts showing the scribe line, respectively. The configuration explanatory diagram, Figure 3, shows four types of SOG.
Using a g-forming solution, Si different from that shown in FIG.
Figure 1 equivalent figure using 0g base film, Figure 4 (a), (
b) are respectively 2nd v! J(λ), a diagram corresponding to FIG. 2(b), and FIG. 5 are different types of SOG in the above embodiment.
Characteristic diagram showing droplet spreading diameter and wettability for film forming solution, No. 615! ill is SO in the above example
Block diagram showing evaluation test of G film forming solution, Fig. 7 (
a) and (b) are diagrams showing different types of scribe lines, and FIG. 8 is an explanatory diagram of the configuration of a dropping device showing one embodiment of the present invention. Fig. 9 is an explanatory diagram for measuring the spreading diameter of the SOG film forming solution dropped using the above two devices, and Fig. 10 (a) is an explanatory diagram of the configuration of the dropping device showing another embodiment of the present invention. , FIG. 10(b) is an explanatory diagram showing a pond measuring means different from the above measuring means for measuring the spreading diameter. 21...Scribe line, 23...Si substrate containing a SiO2 base film on the surface, 24...LS (or chip), 27
-=-... Base PE TEOS (SiOz film)
. 1 Figure scribe line step (, ym) d Figure 2 (a) 23 (b) (i i113 Figure 4 Figure 8 Figure 9

Claims (1)

[Claims] 1. SOG on the semiconductor substrate on which the SiO_2 base film is formed
Drop the film-forming solution dropwise, measure the spreading diameter D per drop, and find D≧6.5 mm or more (however, one drop is approximately
A method for evaluating the performance of a solution for forming an SOG film, the method comprising determining whether the solution is 5ml or not. 2. The SOG film forming solution has the formula Rn-Si (
OH)_4_-_n (However, R represents an alkyl group, and n
2. The method for evaluating the performance of a SOG film forming solution according to claim 1, which comprises an organic solution such as propylene glycol monopropyl ether, butyl cellosolve, or ethanol as a solvent. 3. The method for evaluating the performance of a SOG film forming solution according to claim 2, wherein the concentration of alkylsilanol in the SOG film forming solution is 5 to 20%. 4. Claims 1 to 4 in which a plurality of SOG film forming solutions having different concentrations of alkylsilanol are used simultaneously for determination.
3. The method for evaluating the performance of the SOG film forming solution according to any one of 3. 5. Form a SiO_2 base film on a single or multiple semiconductor substrates by CVD or plasma oxidation, and
2. Drop the SOG film forming solution onto a part of the semiconductor substrate on which the base film has been formed, and measure the spreading diameter D of each drop.
), the selected coating solution is spin-coated onto the SiO_2 base film, and then heat treatment is performed to planarize the semiconductor substrate.
A method for manufacturing a semiconductor device using a method for evaluating the performance of a G film forming solution. 6. SOG film formation comprising a dropping means for dropping an SOG film forming solution onto a semiconductor substrate and a diameter measuring means for measuring the spreading diameter of each drop of the dropped SOG film forming solution. Mechanism for evaluating the performance of liquid solutions.