JPH02249908A - Method for inspecting resist pattern - Google Patents

Abstract

PURPOSE:To accurately measure a tapered angle by providing a mark for aligning an axis near a resist pattern, inclining a substrate corresponding to the side angle of a cross sectional shape and adjusting and operating a scanning type electron microscope based on the mark for aligning the axis. CONSTITUTION:The marks for aligning the axis M and M' are plotted near both sides of the extension of the resist pattern 7 at a production stage by an electron beam. As soon as one side face 13 of the pattern 7 is confirmed once on the screen of a CRT 16 while adjusting an inclination axis, it is made to just disappear by rotating the axis reversely to before. By reading the display of a rotation angle at this time, the tapered angle against the one side face 13 of the pattern 7 is easily measured. Furthermore, the other side face 14 is measured by adjusting the inclination axis in an opposite direction. Namely, the production stage is completed while controlling size by inspecting the cross sectional shape of the pattern 7 and measuring the tapered angle, thereby forming the pattern whose finished degree is high.

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION (Industrial Application Field) The present invention relates to a method for inspecting resist patterns during the manufacture of high-density integrated circuits such as LSIs and VLSIs.

(Prior Art) In recent years, there has been an ever-increasing demand for higher performance and higher integration of semiconductor integrated circuits, etc., and electron beams have been used instead of conventional photolithography using ultraviolet light.

Efforts are being made to establish ultra-fine pattern processing technology using phosphorography using soft X-rays, ion beams, etc. In particular, electron beam lithography has already been put into practical use industrially in the production of photomasks, and direct writing on wafer substrates using electron beams has also been attempted.

On the other hand, in order to make such ultra-fine lithography technology possible, the requirements for exposure equipment's drawing accuracy have become stricter, and the resist materials used must also have characteristics that can meet these requirements, and the resist process must also be extremely demanding. is considered important. Also, although many resists have been developed,
- Numerically, it is classified into positive type, in which the irradiated area is made solubilized by a decay reaction caused by irradiation with electron beams, etc., and negative type, in which the irradiated area is insolubilized by a crosslinking reaction caused by irradiation with electron beam, etc. Ru. Positive resists are superior to negative resists in that they can form ultra-fine, high-resolution images. When attempting to observe the cross-sectional shape of such a resist pattern, a method is usually used in which the resist pattern is broken together with the substrate.

(Problems to be Solved by the Invention) When using the method of observing the cross-sectional shape of a resist pattern as described above, the cross-sectional shape of the resist pattern can be grasped when the substrate can be broken. In the case of a resist pattern formed by the method, it is usually impossible to break the wafer substrate or photomask glass substrate in order to observe its cross-sectional shape. That is, observation of the cross-sectional shape of a resist pattern depends on whether or not the substrate is broken during the manufacturing process.

This invention has been made under these circumstances, and an object of the invention is to:
It is an object of the present invention to provide a resist pattern inspection method that allows easy observation of the cross-sectional shape of the resist pattern and measurement of the taper angle depending on whether or not the substrate is broken.

Structure of the Invention: (Means for Solving the Problems) The present invention relates to a method for inspecting a resist pattern having an inverted trapezoidal cross-sectional shape formed on a substrate using an electron beam, an ion beam, ultraviolet rays, or X-rays. The above-mentioned object of the present invention is to provide a mark for axis alignment using a scanning electron microscope in the vicinity of the resist pattern while forming the resist pattern, and to operate the tendency of the substrate corresponding to the side angle of the cross-sectional shape and the axis. This is achieved by inspecting the cross section of the resist pattern and measuring the taper angle by adjusting the scanning electron microscope based on the marking marks.

(Function) As far as photomask manufacturing and wafer processing are concerned, it is impossible to break them, so various methods such as visual observation of the cross-sectional shape of the resist pattern and measurement of the taper angle using a scanning electron microscope, etc. It is difficult to carry out inspection items.

Therefore, in the present invention, attention is paid to the formation of the resist pattern, that is, the manufacturing process, and a centering mark is provided so that the taper angle can be measured using a scanning electron microscope at the same time as the resist pattern is formed. this is,
It is drawn in the vicinity of both sides corresponding to the extension line of the resist pattern, and in addition to the cross-sectional observation by tending the substrate in the direction toward the side angle of the cross-sectional shape, which is the resist pattern inspection method of the present invention, This facilitates the measurement of the taper angle by adjusting the scanning electron microscope based on the centering mark. In addition to the above-mentioned inspection method, if normal observation from the top is performed, it becomes possible to manage the three-dimensional dimensions of the resist pattern.

(Example) The present invention will be described in detail with reference to Examples below.

Figure 3 (8) to (E) are GaAsMEs related to this invention.
SFET (Metal Sem1 conductor
FIG. 3 is a cross-sectional view showing each step of the manufacturing process of the Field Effect Transistor (Field Effect Transistor) device. Here, for convenience's sake, the explanation regarding the manufacture of a GaAs-MESFET device will focus on the gate portion.

First, as shown in Figure 3 (A), the GaAs before processing is
- The MESFET substrate has an N1 injection layer 3 formed by implanting S++ on one side of a semi-insulating GaAs substrate 5, and an N channel layer 4, and the upper surface of these is irradiated with an ion beam or the like. On the smooth surface 2 obtained by
) is coated with a spinner and heated at 170° C. for about 30 minutes to form a resist film 1 having a thickness of 0.5 μm.

Then, a gate pattern with a width of, for example, 0.3 μm is drawn using an electron beam 6 using an electron beam drawing apparatus shown in FIG. 3(B), and then developed at about 23° C. It was developed by immersing it in Fi (methyl isobutyl ketone: isopropyl alcohol - 1 = 3) for about 1 minute, and after development, it was also immersed and cleaned for 30 seconds using a rinse solution at about 23°C, resulting in the same figure (
A resist pattern 7 as shown in C) is obtained. The cross-sectional shape of the resist pattern 7 at this time is an inverted trapezoid as shown in FIG.

In the manufacturing process, using the resist pattern 7 as a mask, as shown in FIG.
If a WSi film 9 including an i-pattern film 8 is formed on the resist film 1 and then lifted off using acetone, a film with a width of 0.3 μm and a length of 20 μm as shown in FIG.
A 0 um WSi gate 10 is formed. Note that the cross-sectional shape of the resist pattern 7 is made into an inverted trapezoid in order to perform lift-off (dissolution) smoothly.

In this way, a resist pattern is obtained not only for the gate part but also for the source and drain parts, and the WSi source 11 as shown in FIG. 3(E) is obtained.
The entire manufacturing process is completed by forming the WSi train 12.

In the manufacturing process shown in FIGS. 3(A) to (E), the resist pattern inspection method of the present invention shown in FIGS. 1(A) to (C) corresponds to the state shown in FIG. 1(A). As is clear from the above, it is introduced at the stage shown in Figure 3(C). That is, since the resist pattern 7 having a cross-sectional shape of an inverted trapezoid is formed here, a predetermined accuracy inspection is performed on the dimensions of the inverted trapezoid. For example, as shown in FIG. 1B, the substrate is tilted so that one side surface 13 of the resist pattern 7 can be observed in the direction of one side angle of an inverted trapezoidal cross-sectional shape. Furthermore,
Subsequently, as shown in FIG. 1C, the same applies to the direction regarding the other side angle of the resist pattern 7, and the substrate is tilted in the opposite direction so that one side 14 of the resist pattern 7 can be observed. , each cross-sectional shape of the resist pattern 7 is inspected.

By tilting in this manner, the taper angle can be measured using an electron beam 15 of a scanning microscope (not shown) as shown in FIG. 1(B) or (C). Furthermore, if the usual inspection from the top in the state shown in FIG. can. However, it is required that the cross-sectional shape of the resist pattern 7 can be inspected accurately and quickly during the manufacturing process. Therefore, for this purpose, it is desirable to be able to easily measure taper using the electron beam 15 of a scanning electron microscope and to be able to measure it with high precision.

Therefore, in this invention, as shown in FIG. 2, glazing marks M and Mo are placed near both sides on the extension line of the resist pattern.
is drawn by an electron beam 6 during the manufacturing stage shown in FIG. 3(B). Figures 4(A) and (8) to Figure 6 show step by step a method for measuring the taper angle of a resist pattern using a scanning electron microscope using such axis alignment marks M and Mo. The figure explains the operation using the scanning electron microscope at that time.

To measure the taper angle based on the centering marks M and Mo, first, as a reference line on the monitor C87 screen 16 of the scanning electron microscope as shown in FIG. A vertical line 17 longer than the length of the line segment connecting the marks M and Mo is provided, and as shown in FIG. 7A, the rotation angle To of the tilting stage 20 with respect to the tilting axis T in FIG. Keep it fixed.

Next, the X-axis and Y-axis related to the XY stage 19 in FIG. 7 and the rotation angle Rθ of the rotation axis R related to the scanning electron microscope are XY moved and R
While rotating the shaft, follow the moving direction E of FIG. 4 CB) as shown in FIG.

Match to connect. Regarding the specifications of each rotation angle Tθ and Rθ of the scanning electron microscope shown in FIG.
is the rotation relative to the sample stage 18! Rotation angle of lN1hR from 0 to
2.pi., whereas T.theta. is generally determined by using the vertical direction of the rotation axis R as an O reference, and the rotation angle relative to this can be varied from about 0 to ±.pi./3. Further, it is assumed that the horizontal plane F shown in FIGS. 4(A), 5(B), and 6 does not change.

Here, the electron beam 15 of the scanning electron microscope has a tilt axis T
is 0 degrees and is incident on the lock perpendicular to the substrate, so in this state, fix the rotation @R and change the rotation angle of the inclination @T in Figure 7 as shown in Figure 6. By adjusting To, the parallel state between the angle of one side surface 13 of the resist pattern and the electron beam 15 can be obtained, for example, as a tilt IIIIT rotation from the rotation axis Rh) to the rotation axis R° in FIG. Actually, on the C17 screen 16, the resist pattern 7 is adjusted while adjusting the tilt axis T.
Once one side 13 of the resist pattern 7 has been confirmed, the one side 13 of the resist pattern 7 can be immediately turned in the opposite direction so that this one side 13 is no longer visible. The taper angle with respect to 13 can now be easily measured. Furthermore, for the other side surface 14, the tilting axis T may be adjusted in the opposite direction. That is, by inspecting the cross-sectional shape of the resist pattern 7 and measuring the taper angle to complete the manufacturing process while managing dimension control, a highly complete resist pattern can be formed.

The angle of the rising surface of the lift-off pattern with respect to the shape of the resist pattern 7 of the present invention is 1 with respect to the substrate.
It is desirable to have a reverse taper shape of about 00 to +10 degrees,
The axis alignment marks are effective when the length of the resist pattern 7 is relatively short, and the distance between each mark is 5 μm to 500 μm.
μm, and if the shape of the mark is circular, its diameter is 0.
5 μm to 20 μm, and if the shape is a square, one side may be set to 0.5 μm to 20 μm, but this is not a limitation.

Effects of the Invention: As described above, according to the present invention, it is possible to manage the three-dimensional dimensions of a substrate that cannot be broken by observing the cross-sectional shape and the top surface, and it is also possible to easily measure the taper angle. We have realized a method for inspecting resist patterns that can be carried out accurately. In particular, by forming a resist pattern and providing marks for deglazing that are effective for adjustment operations using a scanning electron microscope, it is possible to conveniently measure the taper angle, so the above inspection allows extremely high-precision dimensional control. This makes it possible to reliably form a resist pattern with high quality.

[Brief explanation of drawings]

FIGS. 1(A) to 1(C) are cross-sectional views shown to explain each step of the resist pattern inspection method of the present invention introduced during the manufacturing process of a GaAs-MESFET device;
FIG. 2 is a plan view of a resist pattern shown to explain an example of an axis alignment mark for effective measurement of the taper angle according to the present invention, and FIGS. 3(8) to 3(E) are GaAs- Figures 4 (A) and 4 (B), which are cross-sectional views of each step in the manufacturing process of a MESFET device, illustrate the adjustment at the starting stage of a method for measuring the taper angle of a resist pattern using a scanning electron microscope using an axis alignment mark. Figures 5 (A) and (B) are comparison diagrams of the actual side view and the monitor image on the C87 screen shown for explanation, respectively, and show the intermediate stage adjustment following Figures 4 (A) and (B). FIG. 6 is a comparison diagram of the actual side view shown for explanation and the monitor image on the C87 screen, and FIG. Figure 7 is Figure 4 (A)
, (B) is a perspective view in the three-dimensional axis direction of the scanning electron microscope shown for explaining the operability with respect to FIGS. DESCRIPTION OF SYMBOLS 1... Resist film, 2... Smooth surface, 3... N injection layer 4... N channel layer, 5... Semi-insulating GaA
s substrate, 6...electron beam, 7...resist pattern,
8...WSi pattern film, 9...WSi film, lO・
...WSi gate, 11...WSi source, 12.
...WSi drain, 13.14...One side of resist pattern, 15...electron beam, 16...01
7 screen, 17...vertical line, 18...sample stage, 19...
・XY stage, 20...tilt stage, M, M'・
・・Mark for axis alignment. Applicant's agent Yu Yasugata Figure 3 Figure 3 Figure 3 (A) (B) Figure ♂

Claims (1)

[Claims] 1. In a method for inspecting a resist pattern having an inverted trapezoidal cross-sectional shape formed on a substrate by an electron beam, an ion beam, an ultraviolet ray, or an X-ray, a scanning electron microscope is used near the resist pattern while forming the resist pattern. The cross-sectional inspection and taper of the resist pattern are performed by providing an axis alignment mark according to the method, and by manipulating the tendency of the substrate corresponding to the side angle of the cross-sectional shape and adjusting the scanning electron microscope based on the axis alignment mark. A resist pattern inspection method characterized by making it possible to measure angles.