JPH02246332A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To eliminate fine foreign matter attaching on a wafer by exfoliating a resin film in the state that the foreign matter attaches on the resin film by a method wherein, after the resin film is stuck and formed so as to cover the foreign matter attaching on the substrate, the resist film is treated with alkaline solution. CONSTITUTION:In order to eliminate foreign matter which has attached onto a wafer surface at the time of ion implantation, a second resist 5 is spread in an arbitrary thickness on a resist pattern 3. After that, the wafer is treated by using alkaline solution like mixed solution of ammonia/hydrogen peroxide water/water; the foreign matter can be eliminated while being wrapped by the first and the second resists 3, 5 as it is; these resists exfoliate and drop. At this time, the second resist 5 on the flat wafer exfoliate and drop, while sticking to the resist 3 and turning to one film as it is, Thereby, the eliminated foreign matter is prevented from re-attaching to a semiconductor substrate, so that a clean substrate surface can be maintained.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a semiconductor device manufacturing method for keeping the surface of a semiconductor substrate clean. A resin film is formed on a substrate to which foreign matter is attached, and after the foreign matter is attached to or encased in the resin film, the resin film is peeled off from the semiconductor substrate with the foreign matter attached or encased using an alkaline solution. The structure has a process.

[Industrial Application Field] The present invention relates to a method of manufacturing a semiconductor device for keeping the surface of a semiconductor substrate clean.

Semiconductor integrated circuits in recent years are submicron (0.8~0.
6μ) level. In semiconductor devices, dust with a size of about 1/10 of the minimum line width affects the yield.
As the thickness becomes smaller, it is necessary to control and suppress foreign particles of about 0.1 μnl. Conventional methods for cleaning semiconductor substrates are broadly classified into physical methods and chemical methods, and the former include (a) brush scrubber, (b) high-pressure blow, (c) ultrasonic, and There are methods such as (d) polishing, and the latter include (e) washing with water, and (f) etching (chemicals).
, (g) oxidation/reduction, (h) ashing, and (s) dissolution. Considering the advantages and problems of these methods, (a) the brush scrubber method and (b) the high-pressure blow method remove surface deposits, but they remove adsorbed substances that are physically or chemically adsorbed on the surface. Objects are not removed.

In the ultrasonic removal method (c), surface deposits are removed, but the surface of the crystal is damaged by the ultrasonic waves, resulting in defects such as point defects. In the polishing method (d), not only deposits but also adsorbed substances are removed, but polishing cannot be performed after the element is formed.The water washing method (e) is effective in removing soluble inorganic substances. However, it is hardly effective in removing foreign substances contaminating semiconductor substrates.The etching method (to) can remove foreign substances along with the substrate surface by dissolving the substrate surface, but it does not roughen the substrate surface. The oxidation/reduction method in (g) aims to remove foreign substances by converting them into substances that easily volatilize, but it has little effect on removing foreign substances. (b) The dissolution method has advantages and disadvantages, such as being effective in removing organic substances but not in removing non-filament substances.

As mentioned above, none of the methods is perfect, so we assume the type of foreign object that is most likely to occur, and then select the removal method.
Currently, foreign substances are removed using a combination of three methods.

In this way, it is difficult to remove foreign matter that has adhered to the substrate, etc., so the basics of cleaning have traditionally been to first prevent the generation of fine particles, secondly to prevent them from adhering, and thirdly to remove them. Although there are many cleaning methods that target large particles of 5 to 10 μm, it was thought that these methods could not be expected to clean fine particles of the order of 0.1 μm ( VLSI Manufacturing Technology, Nikkei BP, published January 14, 1989, 1st edition, 1st printing, page 269).

In particular, dry etching and
During ion implantation, foreign matter is likely to be generated due to friction in the etching equipment, the movable parts of the ion implantation equipment, the substrate holding parts, etc., and the foreign matter that has adhered or adsorbed in this way, as well as the foreign matter contained in the resist itself, may be removed during resist dissolution. It was eluted into the recommended product and redeposited on the surface of the semiconductor substrate. In order to avoid this, chemicals have been filtered during dissolution and removal, or various combinations of the above-mentioned cleaning methods have been used to remove the chemicals, but it has been difficult to completely remove them.

[Problem to be solved by the invention] Conventionally, there was no effective means for removing foreign matter such as submicron particles or dust that adhered to a wafer.For example, foreign matter that re-attached during resist dissolution and removal could be However, there has been a problem in that defects occur in patterns and films. Therefore, a resist removal method that prevents foreign matter from re-adhering has been desired.

An object of the present invention is to provide a means for removing dark blue foreign matter attached to a wafer.

[Means for Solving the Problems] A first aspect of the present invention is to form a resin film so as to cover foreign matter adhering to a substrate, and then treat the foreign matter with an alkaline solution so that the foreign matter is removed from the resin film. while attached to
The method for manufacturing a semiconductor device includes the step of peeling off the resin film, and the second step is to form a second resin film so as to cover foreign matter adhering to the first resin film formed on the substrate. Then, by treating with an alkaline solution, the first resin film and the second resin film are separated while the foreign matter is entrapped in the first resin film and the second resin film. This is a method of manufacturing a semiconductor device, which includes the steps of:

1 (A) to (C) are drawings for explaining the principle of the present invention in an example of removing foreign matter attached to the wafer surface during ion implantation. In drawing 0, 1 is a semiconductor substrate, 2
1 is an insulating film such as 5i02, and 3 is a resist pattern. In FIG. 1A, impurity ions are implanted into the semiconductor substrate 1 using this resist pattern 3 as a mask. 4
are foreign substances that adhere to the wafer surface during wafer handling.According to the present invention, the resist pattern 3
A second resist 5 is applied to an arbitrary thickness on top (hereinafter referred to as the first resist 3) (FIG. 1).

Thereafter, when the wafer is treated with an alkaline solution such as a mixture of ammonia/hydrogen peroxide/water, the foreign matter 4 can be removed while being wrapped in the first and second resists, and these resists 3.5 can be removed. It peels off. At this time, if the second resist 5 is on a flat wafer, it may peel off as a single film while adhering to the resist 3, and/or if the wafer has a large height difference, the second resist 5 may peel off at the step. The resist 5 is divided and peeled off, but this resist 5 is not dissolved by the alkaline solution, but peels off from the wafer at the interface with the insulation M2. If the resist 5 is dissolved in an alkaline solution, there is a risk that the foreign matter 4 will float in the solution and re-adhere to the wafer. According to the method of the present invention, the first resist 3 and the second resist 5
Not only the foreign matter 4 in between, but also the foreign matter 4 on the semiconductor substrate 1,
It can be removed while being incorporated into the second resist (5).

As described in "U," this method allows foreign matter on the resist and foreign matter from the substrate to be peeled off while being enveloped in the resist, making it possible to remove the resist without causing the foreign matter to re-adhere. At this time, since the alkaline solution etches the SL, SiO□, etc. only at an extremely slow etching rate of several angstroms per minute or less, roughening of the wafer surface due to its use does not pose a problem.

Even if the first resist 3 and the second resist 5 are made of different materials, the above foreign matter can be removed, but a reactive substance is generated at the interface between the resists, and peeling occurs at the interface between the resists 3 and 5 during alkaline solution treatment. Therefore, it is preferable to use the same type of resist.

The first aspect of the invention is to form a resin film so as to cover the foreign matter adhering to the substrate as described above, and then treat it with an alkaline solution so that the foreign matter remains attached to the resin film. This is to peel off the resin film.

The second invention is to form a second resin rPA5 on the first resin film 3 formed on the substrate so as to cover the foreign matter, and then treat it with an alkaline solution to remove the foreign matter. The first resin fi3 and the second resin film 5 are separated from each other in a state where they are surrounded by the first resin film 3 and the second resin film 5.

[Function] Hereinafter, the function of the present invention will be explained with reference to FIG. 2, which shows the processing procedure in the experiment, and FIG. 3, which shows the foreign matter removal ability. As shown in FIG. 2, first, the number of foreign particles on the wafer was measured, and then an alkaline solution treatment was performed with the foreign particles sandwiched between the first resist 3 and the second resist 5. 1), a 6-inch wafer was used as the semiconductor substrate, and the so-called RCA cleaning method, which is conventionally used for surface cleaning and purification of St substrates, was used as the alkaline solution treatment. Alternative method (second method)
In the specific example of the invention), a wafer with foreign matter 4 attached to the first resist 3 was not treated with an alkaline solution, but after the alkaline solution treatment, the wafer was washed with water and dried, and the number of foreign matter was measured. The results are organized according to the size of the foreign object and are shown in Figure 3.
Based on the data without cover resist in this figure, RCA cleaning (
It can be seen that the alkaline solution) has the effect of removing foreign matter of 0.2 μm or more. In addition, the method of removing foreign matter by inserting it between the resists is about 1/10th as compared to RCA cleaning alone.
It can be seen that the number of foreign objects has decreased.

Therefore, when the number of foreign particles is small, only the alkaline solution treatment is performed, and when the number of foreign particles is large, the foreign materials are sandwiched between the resists and the alkaline solution treatment is performed.

[Example] The present invention will be described in detail below with reference to one drawing.

Embodiment 1 (Fig. 4 - Dry etching process) In Fig. 4 (A), when removing polysilicon film using the first resist 3 as a mask, in order to remove foreign matter 4 attached to the wafer, , in FIG. 4(B), the thickness is 1~
A 5 μm second resist 5 is applied to the entire surface of the wafer, dried and heated to harden the film to a certain degree of hardness, and then coated with an NH4OH/H20□ based liquid (volume ratio 1.5:
1:4) or with KOH/Hz O base solution in Figure 4 (
As shown in C), the first and second resists 3.5 are treated for 5 to 10 minutes with the foreign matter 4 taken in, and then removed.

Note that the resist film thickness, liquid composition, and processing time described above are the same in the following examples.

Example 2 (Figure 5 - Ion implantation process) Figure 5 (A)
, the first resist 3 is placed around the polysilicon layer.
In the step of implanting impurity ions only around the polysilicon layer, a second resist 5 is applied as shown in FIG. In (C), the first and second resists 3 and 5 are peeled off.

Example 3 (Fig. 6, shrimp growth pre-treatment) As a pre-treatment for epitaxial growth, it is necessary to remove the oxide film on one side of the S1 wafer etc. by hydrofluoric acid etching, etc. At this time, the resist used as a mask 3 (Fig. 6 (A) and (B)) were conventionally removed using sulfuric acid or oxygen plasma. However, dust floating in the sulfuric acid and fragments of the quartz chamber of the oxygen plasma generator adhered to the wafer. There was a problem that sulfuric acid itself is quite contaminated even when it is new before use, and it does not have the ability to dissolve dust, so dust accumulates in the sulfuric acid during use, so when removing resist 3, 'l! Objects stick to each other.

Therefore, when resist stripping using an alkaline solution according to the present invention is carried out as illustrated in FIG. 6(C), the adhesion of dust accompanying the resist removal is eliminated, but the foreign matter 4 attached to the resist 3 due to the hydrofluoric acid treatment is also removed from the resist. It can be removed along with the

Furthermore, it is also possible to apply a second resist on the resist 3 and peel off these resists all at once.

Example 4 (Fig. 7, Fig. 8 - Unibar trimming) For example, when trimming a 6-inch Si y7:r bar to 4 inches, it adheres to pieces of Sl and becomes foreign matter. According to the method of the present invention. and a wafer l whose surface is covered with an oxide film.
The first resist 3 (FIG. 7(A)) is applied to one side of the wafer.Next, the wafer is placed on the rotary table 7 and the peripheral edge is removed with a cutter (FIG. 7(B)).At this time, Foreign matter 4 adheres to the upper and lower surfaces of the wafer. Therefore, as shown in FIG. 7(C), a second resist 5 is applied on top of the first resist 3, and then an alkaline solution treatment (FIG. 7(D)) is performed. The first test is performed with a foreign object sandwiched between the resists.
, the second resist 3.5 is peeled off, and at the same time, the foreign matter 4 adhering to the exposed insulating film also separates from the insulation J]12.

Figure 8 (A>, (El) are respectively Figure 7 (C), (D
), the process of further applying the second resist 5 and performing alkaline solution treatment is shown.

Embodiment 5 (FIG. 9 - Isolation) In FIG. 9 (A>), a trench 1'' connected to the buried layer 1° is formed by anisotropic etching, and polysilicon is deposited on the entire surface.

After that, KOH-10% solution and Al2O3≦0.0
Etching and polishing with an abrasive cloth containing 5%
The polysilicon layer on the surface is removed (FIG. 9(B)).

Next, as shown in FIG. 9(B), the first resist 3 is applied,
In FIG. 9(C), alkaline solution treatment is performed.

[Effects of the Invention] As explained above, according to the present invention, by entrapping foreign matter in the resist and peeling it off, the removed foreign matter does not re-adhere to the semiconductor substrate, thereby maintaining a clean substrate surface. This eliminates pattern defects and defects, which improves the reliability of devices and improves yield. At the same time, the process is completed in one cleaning process, which reduces the processing time compared to when conventional cleaning processes are combined. The time is shortened and high throughput is possible.

[Brief explanation of drawings]

Figures 1 (A) to (C) are diagrams explaining the principle of the present invention, Figure 2 is a flowchart of the experimental procedure, Figure 3 is a diagram showing the effect of removing foreign substances, and Figures 4 (A) to <C> are dry A process diagram showing an example of the etching process, Figures 5 (A) to (C) are process diagrams showing an example of the ion implantation process, and Figures 6 (A) to (C) are examples of the epitaxial growth pretreatment. 7 (A) to (D) and 8 (A) and (B) are process diagrams showing an example of wafer trimming. It is an example process diagram. 1-semiconductor substrate, 2-insulating film, 3-first resist, 4
-Foreign matter, 5-Second resist patent applicant Fujitsu Ltd.Research and separation Fig. 1 (C) Ion insertion process Fig. 1 (A) Revstner ramie Fig. 1 (B) Tora test section 11 F D -1↑-1- Fig. 2 Effect of foreign matter removal when n is lost. Fig. 3. (B) Ion intrusion Fig. 5 (A) Fig. (8) Revus F-Keiyumi Fig. 5 (C) Fig. (A) Wafer hirimi'/7゛ Fig. 7 (B) Fig. (A) D ) Relay thickness Fig. 8 (A) Eno ν force °j / raw stone grilling Fig. 8 (B) Filler thickness Fig. 9 (A) Ef thickness Fig. 9 (B)

Claims (1)

[Claims] 1. A resin film is formed to cover the foreign matter attached to the substrate, and then treated with an alkaline solution, so that the resin film is removed while the foreign matter is attached to the resin film. A method for manufacturing a semiconductor device, comprising the step of peeling off a film. 2. A second resin film is deposited on the first resin film formed on the substrate so as to cover the foreign matter attached, and then,
By treating with an alkaline solution, the foreign matter is removed first.
A method for manufacturing a semiconductor device, comprising the step of peeling off the first resin film and the second resin film while the semiconductor device is surrounded by the resin film and the second resin film.